Question

A car rental agency charges ​$50 per week plus ​$0.50 per mile to rent a car.

Answer 1

The cost in dollars is given as 50 + 0.50x, so ...
f(x) = 0.50x +50

B) You want to find x for f(x) = 100. Substitute the given numbers and solve for x.
100 = 0.50x +50
50 = 0.50x
50/0.50 = x
100 = x
You drove 100 miles during the week if the cost was $100.