Question

4a I do not understand the process

Answer 1

The answer is 9/40.

All you need to do is subtract 5/8 - 2/5 and to do that, you would need a common denominator. So just,

5 2
— —
8 5

Multiply the two bottoms to get 40 and do the same thing with the top that you did with the bottom so....

5 x 5 = 25
— —
8 x 5 = 40

2 x 8 = 16
— —
5 x 8 = 40

Subtract 25 - 16 = 9 and keep the denominator the same so 9/40 is your answer.

Answer 2

9/40

Explanation:

He needs 5/8, he already has 2/5, so still needed is 5/8-2/5.

To add or subtract fractions, the denominators must be equal.

Simplest approach is to multiply them. 8 times 5 is 40, so 40 is the new denominator we need for both fractions.

So first we convert 5/8 to 25/40.

Then we convert 2/5 to 16/40.

Now we can subtract them:

25/40 - 16/40 = 9/40.

9/40 cannot be simplified so this is the final answer.

There are some basic rules you need to know to work with fractions. If above work is too fast, comment below for deeper explanation.