A phone company offers two monthly plans. Plan A costs $15 plus an additional $0.14 for each minute of calls. Plan B costs $20 plus an additional $0.09 for each minute of calls. For what amount of calling do the two plans cost the same?

How to solve the problem--step-by-step:

m=each minute

plan A:

$15+$0.14x

plan B:

$20+$0.09x

Solve

15+0.14x=20+0.09x

15-15+0.14x=20-15+0.09x

0.14x=5+0.09x

0.14x-0.09=5+0.09x-0.09

0.05x=5

0.05x/0.05=5/0.05

x=100

Thus, at 100 minutes, the two plans cost the same.

Check Work

plan a: 15+0.14 (100) = $29

plan b: 20+0.09 (100) = $29

Solution is correct.