Write a sentence about different ways to show subtraction for a problem like 32-15

Proposed statement/question:
Jonathan has 32 math problems to do by the weekend.
On Thursday he completes 15 math problems. How many more math problems does Jonathan need to finish in order to be done before the weekend? 

The answer to this question would be as follows:
Total questions to answer is 32
Number of questions answered is 15
Number of questions left is unknown

Therefore:
Total questions to answer = questions answered + questions left
32 = 15 + questions left
questions left = 32 - 15

How much is 32 out of 40 written as a percentage? convert fraction (ratio) 32 / 40 answer:   80%