marcel earned $32 for 4 hours of work. show how to use a proportion to find how many hours, h, he must work to earn $80

He earned 32 for 4 hours, so you have 32/4.

Then you want to find the number of hours to make 80, so you have 80/h.

Set them to equal each other:

32/4 = 80/h

Now cross multiply:

(32 * h) / (4 * 80)

Simplify:

32h = 320

Divide both sides by 32:

h = 320 / 32

h = 10

He will need to work 10 hours.