# Video: KS2-M16 • Paper 1 • Question 27

(3/10) − (1/20) = ＿.

01:54

### Video Transcript

Three-tenths subtract one twentieth equals what?

These fractions have different denominators. We’ve got three-tenths and one twentieth. To help us subtract, both fractions need to have the same denominator. We need to find the lowest common multiple of 10 and 20, which is 20. 20 is a multiple of 10. So we don’t need to do anything to the one twentieth. We just need to change our three-tenths into twentieths.

To get from 10 to 20, we need to multiply by two. We need to do the same to the numerator. So what is three multiplied by two? Six. Now we can calculate six twentieths take away one twentieth, which equals five twentieths. So three-tenths take away one twentieth is equal to five twentieths.

We could simplify this fraction. Five twentieths is equal to one-quarter. We can simplify the fraction by dividing the numerator and the denominator by five. Five divided by five is one. 20 divided by five is four. One-quarter is also a correct answer because five twentieths is equal to one-quarter.