SOMEONE PLEASE BREAK THIS DOWN

Question

The phone company calculates a customer’s monthly cell phone bill as follows:
monthly service charge: $40
voice charges:
First 100 minutes: $0.021 per minute
Second 100 minutes: $0.037 per minute
Additional minutes: $0.048 per minute
a. What is the charge for a month in which 153 minutes were used?
b. What is the charge for a month in which 317 minutes were used?
c. Construct a piecewise function that gives the monthly charge for x minutes of usage

Answer 1

a. 100(0.021) + 53(0.037) + 40 = your answer

 

b. 100(0.021) + 100(0.037) + 117(0.048) + 40 = your answer

 

c.           0.021x + 40 if x ≤ 100

    f(x) = 0.037(x - 100) + 40.021 if 100 < x ≤ 200

              0.048(x - 200) + 40.058 if x > 200