4a I do not understand the process

9/40

Step-by-step 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.

the answer is c. 23/3

any options?

step-by-step explanation: