A cell phone company charges a monthly rate of $12.95 and $0.25 a minute per call. The bill for m mi

A cell phone company charges a monthly rate of $12.95 and $0.25 a minute per call. The bill for m minutes is $21.20. Write an equation that models this situation.

Let m be the number of minutes. We have the cost equation C(m):
0.25m + 12.95 = $21.20