Answer:
8 hours
Explanation:
Create an equation that sets the costs equal to each other, where h is the number of hours
3.5h + 20 = 4.75h + 10
Solve for h
3.5h + 20 = 4.75h + 10
20 = 1.25h + 10
10 = 1.25h
8 = h
So, it will take 8 hours for the costs to be equal