Mary repairs microwaves. her revenue is modeled by the function r(h)=20+30h for every h hours she spends repairing microwaves. her overhead cost is modeled by the function c(h)=10h2−80 . after how many hours does she break even? enter your answer in the box.

After 5 hours, Mary will be at the break even point.

To answer this question, we need to find the time when the cost equals the revenue.

Therefore, set our equations equal to each other and solve.

20 + 30h = 10h^2 - 80
0 = 10h^2 - 30h - 100
0 = h^2 - 3h - 10
0 = (h - 5)(h + 2)

Our solutions are h = 5 or h = -2. Only 5 hours makes sense in the context of this problem.