How many calls did he make?

Question

A promotional deal for long distance phone service charges a $15 basic fee plus $0.05 per minute for calls. Its joses phone bill was $60, how many minutes of phone calls did he make?

Answer 1

Let y = total cost of phone bill

Let x = total minutes of phone calls

y = mx + b

60 = .05x + 15       Subtract 15 from both sides

45 = .05x               Divide both sides by .05

x = 900 minutes