Question

A phone company offers two monthly plans. Plan A costs $30 plus an additional $0.15 for each minute of calls. Plan B costs $16 plus an additional $0.20 for each minute of calls.

For what amount of calling do the two plans cost the same?
What is the cost when the two plans cost the same?

Answer 1

Lets m = number of minutes calls

Plan A : 30 + 0.15 m
Plan B: 16 + 0.20 m

For what amount of calling do the two plans cost the same?

30 + 0.15m = 16 + 0.20m
0.05m = 14
m = 280

280 minutes of calling, the two plans cost the same

What is the cost when the two plans cost the same?


Plan A: 30 + 0.15 m = 30 + 0.15 (280) = 72

Plan B: 16 + 0.20 m = 16 + 0.20 (280) = 72

answer

It's cost $72 when the two plans cost the same

Answer 2

Plan A = 30 +0.15x

Plan B = 16 +0.20x

30+0.15x = 16+0.20x

subtract 16 from each side

14 +0.15x = 0.20x

subtract 0.15x from each side

14=0.05x

x = 14/0.05 = 280 minutes

280*0.15 = 42 +30 = $72

280 * 0.20 = 56 +16 = 72

280 minutes and cost $72 each