A phone company offers two monthly plans. Plan A costs $9 plus an additional $0.12 for each minute of calls. Plan B costs $15 plus an additional $0.07 for each minute of calls. For what amount of calling does the to plans cost the same? What is the cost when the to plans cost the same?

Step-by-step explanation:

Let x represent the number of minutes of call for which both plans would cost the same.

Plan A costs $9 plus an additional $0.12 for each minute of calls. This means that the total cost of using plan A for x minutes would be

9 + 0.12x

Plan B costs $15 plus an additional $0.07 for each minute of calls. This means that the total cost of using plan B for x minutes would be

15 + 0.07x

For both costs to be the same,

9 + 0.12x = 15 + 0.07x

0.12x - 0.07x = 15 - 9

0.05x = 6

x = 6/0.05 = 120 minutes

The cost when the two plans will cost the same is

15 + 0.07 * 120 = $23.4