Lisa is comparing two phone plans from two different compani

Lisa is comparing two phone plans from two different companies. Company A has a $100

starting fee and charges $75 per month. Company B has a $25 starting fee and charges $90 per

month. At what month would the cost of both companies be the same? Overall, which is the

cheaper plan over the course of 12 months?

Let the no. of months be x

Company A has a $100 starting fee and charges $75 per month

So, C(x) = 100 +75x

Company B has a $25 starting fee and charges $90 per month

C(x) = 25 +90x

month would the cost of both companies be the same

100 +75x = 25 +90x

15x = 75 ----> x = 5

In 5th month cost of both companies becomes same

Cost of company on x =12 for company A : = 100 +75*12 = $1000

Cost of company on x =12 for company B : = 25 +90*12 = $1105