CPM Homework Help : MC2 Problem 8-20

Mr. Benesh is in charge of facilities at Walt Clark Middle School. He is organizing a project to paint all $36$ classrooms during the school’s summer break. He estimates that it will take one person five hours to paint each classroom.

How many total hours would it take for one person to paint all of the classrooms?
Hint (a):
If it takes five hours for one person to paint one classroom, how many hours would it take to paint $36$ classrooms?
Answer (a):
$180$ hours

Mr. Benesh has a team of four workers he is planning to assign to the job. Assuming they all paint at the same rate of five hours per classroom, how many hours would it take the team to do the painting?
Hint (b):
With a team of $4$ , it would take five hours to finish painting $4$ classrooms. If they wanted to paint all 36 classrooms, how many sets of classrooms would they have to paint, or how may would each person have to paint?
More Help (b):
$36 ÷ 4 = 9 \text{ sets}$
Mr. Benesh realized that he needs the painting to be finished in nine hours so that a different team can come in to wax the floors before school starts. How many people will he need to assign to do the painting in order to do this?
Hint (c):
Based on part (a), all $36$ classrooms would take a total of $180$ hours of work.
Answer (c):
$20$ people