Adding and Subtracting Unlike Fractions

Let's quickly revise about like and unlike fractions.

Fractions with same denominators are called like fractions.

Fractions with different denominators are called unlike fractions.

Examples of unlike fractions with same numerators and different numerators

We also know that two like fractions are added as shown,

Two like fractions are subtracted as shown,

Now, let's add or subtract unlike fractions.

Adding Unlike Fractions

To add or subtract unlike fractions we first convert them to like fractions

Unlike fractions can converted into like fractions either by finding equivalent fractions or by finding LCM of the denominators.

Add the above unlike fractions

We first find the equivalent fractions of the given unlike fractions

The equivalent fractions of and with the same denominator 15 are as shown

Now add the equivalents fractions of and

Let us now Add the above unlike fractions using LCM method,

Since the denominators are not same, first find the LCM of 3 and 5, which is 15

Subtracting Unlike Fractions

Subtract the above two unlike fractions,

Since the denominators are different, let's find the equivalent fractions,

The equivalent fractions of and with the same denominator 20 are as shown

Now subtract the equivalents fractions of and as we did for like fractions as shown

Subtract the above two unlike fractions using LCM method.

Since the denominators are not same, first find the LCM of 5 and 4, which is 20

Revision

Unlike fractions can converted into like fractions either by finding equivalent fractions or by finding LCM

The equivalent fractions of and with the same denominator 20 are as shown

The End