Mathematics | Class: JSS1 | Term: 1st

Addition and Subtraction of Fractions

len Alfred Ajibola - 01st February, 2026 @ 09:17 PM

Topics in Mathematics

Linear Equation in Mathematics Word Problems leading to Algebraic Expression BODMAS in Algebra Multiplication and Division in Algebra Addition and Subtraction in Algebra Multiplication of Number Bases Subtraction of Number Bases Addition of Number Bases Division of Number Base Number Base Conversion Number Base System Significant Figures Rounding Off Numbers Decimal Place Value Fraction Word Problems Word Problems in Fraction Multiplication and Division of Fractions Addition and Subtraction of Fractions Expressing One Quantity as a Percentage of Another Expressing One Quantity as a Fraction of Another


Academic Questions in Mathematics

Please click here to see all Questions and Answers

Decagon - Len Academy

What type of polygon is shown in the above image?

  • A. Nonagon

  • B. Decagon

  • C. Octagon

  • D. Hexagon

  • E. Hepagon

  • F. Pentagon

Which of the following is not part of a circle?

  • A. Section

  • B. Sector

  • C. Segment

  • D. Semicircle

  • E. Secant

  • F. Center

Acute Angle - Len Academy

What angle is shown in the above image?

  • A. Complementary

  • B. Supplementary

  • C. Acute

  • D. Obtuse

  • E. Reflex

  • F. Straight

An angle greater than 90o but less than 180o is termed _____.

  • A. Complementary

  • B. Supplementary

  • C. Acute

  • D. Obtuse

  • E. Reflex

  • F. Straight

Factorize 12a2 - 20a + 3

  • A. (6a - 1)(2a - 3)

  • B. (6a - 1)(2a + 3)

  • C. (6a + 1)(2a - 3)

  • D. (6a + 1)(2a + 3)

  • E. (-6a + 1)(2a - 3)

  • F. (-6a + 1)(2a + 3)

Simplify 10ab + 7ab

  • A. 17ab2

  • B. 17a2b2

  • C. 3ab2

  • D. 3a2b2

  • E. 17ab

  • F 3ab

Which of the following is not a type of angle?

  • A. Right angle

  • B. Left Angle

  • C. Acute Angle

  • D. Complete Angle

  • E. Straight Angle

  • F. Reflex angle

Two lines that can never meet each other are best considered as _____ lines.

  • A. straight
  • B. vertical
  • C. horizontal
  • D. parallel
  • E. oblique
  • F. perpendicular



Addition and Subtraction of Fractions 


The addition of fractions is done by finding a common denominator (bottom number) through the Lowest Common Multiple (LCM), followed by adding the numerators (top numbers) over the common denominator. For example, in the addition of 2/4 + 1/4, since the denominators are already the same, we'll simply add numerators and this equals 3/4.

Note: In the case of subtraction, the above procedure is followed except that we will subtract the numerator. For example 2/4 - 1/4 = 1/4 (since the denominators are equal).

Please read on LCM here.

 

However, if the denominators are different, we'll need to follow these steps below (which is applicable to both addition and subtraction respectively):

  1. Find the Lowest Common Multiple (LCM) to get a common denominator 

  2. Divide the common denominator (derived from the LCM) by each denominator present in fraction.

  3. Multiply the result of each by its respective numerator, separating each result with the plus or minus sign.

  4. Add or Subtract your values depending on the question.

  5. The addition or subtraction of your values over the common denominator becomes your answer.

Please read on the multiplication and division of fractions here.

 


Worked Examples on Adding Fractions 


Example 1
  • 1/5 + 3/5

Solution 

Since the denominators are equal, just add the numerators

1/5 + 3/5 = 4/5

  • 4/5

 

Example 2
  • 1/2 + 1/3

Solution 

Since the denominators are different, we'll find the LCM

1/2 + 1/3

The LCM of 2 and 3 is 6

1/2 + 1/3
       6
3 + 2
   6
  • 5/6

 

Example 3
  • 6 5/12 + 3 3/4

Solution 

First Method 

Convert to Improper Fraction

77/12 + 15/4

The LCM of 12 and 4 is 12

77/12 + 15/4
         12
 
77 + 45
    12

122/12

10 2/12

  • 10 1/6

 

Second Method

6 + 3 + (5/12 + 3/4)

9 + (5/12 + 3/4)

Solve for the fractions 5/12 + 3/4

The LCM of 12 and 4 is 12

9 +  (5/12 + 3/4)
                12
9 +  (5 + 9)
           12

9 + (14/12)

9 + (1 2/12) 

9 + 1 1/6

  • 10 1/6

 

Example 4
  • 2 1/4 + 3 1/4

Solution

Convert to improper fraction

9/4 + 13/4

Since the denominators are equal, just add the numerators

9/4 + 13/4 = 22/4

5 2/4

  • 5 1/2

 

Example 6
  • 1 1/2 + 2 1/3 + 3 1/4

Solution 

Convert to improper fraction 

3/2 + 7/3 + 13/4

The LCM of 2 , 3 and 4 is 12

3/2 + 7/3 + 13/4
           12
 
18 + 28 + 39
         12

85/12

  • 7 1/12

Please read on word problems leading to algebraic expressions here.

Please read on the use of BODMAS in mathematics here.

 


Worked Examples on Subtracting Fractions


Example 1
  • 8/10 - 2/10

Solution

Since the denominators are equal, just subtract the numerators

8/10 - 2/10 = 6/10

  • 3/5

 

Example 2
  • 8/10 - 2/3

Solution 

Since the denominators are different, we'll find the LCM

8/10 - 2/3

The LCM of 10 and 3 is 30

8/10 - 2/3
      30
24 - 20
    30

4/30

  • 2/15

 

Example 3
  • 6 5/12 - 3 3/4

Solution 

Convert to improper fraction

77/12 - 15/4

The LCM of 12 and 4 is 12

77/12 - 15/4
         12
77 - 45
    12

23/12

  • 1 11/12

 

Example 4
  • 4/5 - 2/3

Solution 

The LCM of 5 and 3 is 15

4/5 - 2/3
      15
12 - 10
    15
  • 2/15

 

Example 5
  • 10 3/8 - 4 1/8

Solution 

Convert to improper fraction

83/8 - 33/8

Since the denominators are equal, just subtract the numerators

83/8 - 33/8 -> 50/8

6 2/8

  • 6 1/4

 

Example 6
  • 5 3/4 - 2 7/8 + 1 1/2

Solution 

Convert to improper fraction 

23/4 - 23/8 + 3/2

The LCM of 4, 8 and 2 is 8

23/4 - 23/8 + 3/2
              8
46 - 23 + 12
         8

11/8

  • 1 3/8

Please read on the subtraction of number bases here.

Please read on word problems leading to fractions here.

 


Assignment on Addition and Subtraction of Fractions 


Solve the following fractions.

  • 3/8 + 2/5 - 1/4

  • 3/8 - 2/5 + 5/6

  • 3/4 + 2/3 - 1/2

  • 3/4 - 2/3 + 1/2

  • 8/9 + 4/5 - 3/4

  • 8/9 - 4/9 + 2/3

  • 1 + 3/4

  • 1- 3/4

  • 5 1/5 + 3 7/8 - 3 3/4

  • 5 1/5 - 3 7/8 + 9 3/4

  • 7 3/12 + 7 1/14

  • 7 3/12 - 7 1/4

  • 11/15 + 2/5

  • 11/15 - 2/5

  • 3 1/15 + 2/5

  • 3 1/15 - 2/5

  • 1 1/2 + 3/4 + 4/5 - 1/2

  • What is the sum of 1 7/12 and 3 7/8

  • What is the difference between 4 3/8 and 3 11/12

  • 1 1/2 - 3/4 - 4/5 + 1/2

  • Find the sum of 2 3/4 and 2 4/5. Find the difference between this sum and 6

Please read on mathematics week 6 topic for jss1 first term here.

Please read on mathematics scheme of work for jss1 first term here.

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Amazing facts in Mathematics

The opposite sides of a dice will always give a sum of seven

31,556,926 seconds makes one year

From 0 through 1000, the only number that has the letter 'a' in it is 'one thousand'

÷

The division symbol '÷' is actually called an obelus

Four is the only number in the English language that is spelt with the same number of letters as the number (4) itself

40 is spelt as forty and not 'fourty'. It is the only number that is spelt with letters arranged in alphabetical order

An odd number is a number that cannot be divisible by 2.

Every odd number has an 'e' in its spelling. They include:

  • One
  • Three
  • Five
  • Seven
  • Nine

555 in Thailand sounds like 'hahaha'. This is because the number '5' means 'ha' in Thailand

In mathematics, 10! means 10 factorial. Below is its calculation:

10! = 10 x 9 x 8 x 7 x 6 x 5 x 4 x 3 x 2 x 1 = 3628800

Interestingly, 3628800 seconds is the same as 42 days

42 days is the same as 6 weeks

We can therefore say that 10! equals 6 weeks or 3628800 seconds in mathematics

When you multiply 111,111,111 by 111,111,111; the result equals 12,345,678,987,654,321


Notable points in Mathematics

Let's use algebra to explain the simple statement below:

I am a number. When you subtract 3 from me, the result is 9. what number am I ?

Of course we know the answer is 12. You probably guessed it from your mind because it was that simple. The truth is, We could have a much more complicated statement of such; and that is where algebra comes into play.

Now, to apply algebra in the above statement, we use letters or alphabets to represent the unknown number(s). So using algebra, we can write:

  • Let the number be y

  • y - 3 = 9

  • y = 9 + 3

  • y = 12

Please read more on algebra here

Sides of a right angle triangle - Len Academy

 

The image above shows a right angled triangle. The angle of the above right triangle is denoted as θ. Below are some points to note:

Hypotenuse is always the longest side of the triangle.

Opposite is the side opposite the angle (θ)

Adjacent is the shorter side next to the angle (θ)

Each of Sin θ, cos θ and tan θ are the ratio of sides of the right triangle. They are calculated by using the formula (margic word) sohcahtoa:

Sohcahtoa - Len Academy

soh

Sin θ = Opposite/Hypotenuse

cah

Cos θ = Adjacent/Hypotenuse

toa

Tan θ = Opposite/Adjacent

Please read more on sine, cosine and tangent here

Circumference of a Circle - Len Academy

Circumference in mathematics means the distance around the edge of a circle (or a another curved surface).

Circumference is to circle or any other curved surface

Perimeter of a Rectangle - Len Academy

Perimeter means the distance around a square or rectangle or polygon.

Perimeter is to square or rectangle or polygon