Subtraction

We have learnt to add and subtract like fractions. It is also not very difficult to add fractions that do not have the same denominator. When we have to add or subtract fractions we first find equivalent fractions with the same denominator and then proceed.

What added to 15 gives 12? This means subtract 15 from 12 to get the required number.

Since 15 and 12 are unlikelike fractions, in order to subtract them, we first find their equivalent fractions with the same denominator.

These are 210 and 510 respectively.

This is because 12 = 1×52×5 = 510105 and 12 = 1×25×2 = 2101012

Therefore, 12 - 15 = 510 - 210 = 5−210 = 310103

Note that: is the least common multiple (LCM) of 2 and 5.

Subtract 34 from 56.

Instruction

Solution :

Simplify 35 - 720.

Solution :

The LCM of 5 and 20 is .

Therefore, 35 - 720 = 3×45×44×45×4 - 720

= - 720

= (Simplified form)