Question

A phone company offers two monthly plans. Plan A costs $16
plus an additional $0.10
for each minute of calls. Plan B has no initial fee but costs $0.14
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

We can write two equations for this. x = each minute of calls

Plan A = .1x + 16
Plan B = .14x

Make the two equations equal each other, so we can find when they are the same.

.1x + 16 = .14x

Subtract .1x from both sides

16 = 0.04x

Divide by 0.04 to get x by itself

400 = x.

Earlier, we set x as each minute of calls. This means that after 400 calls, Plan A and Plan B will cost the same.

To find the cost, substitute 400 into both equations by themselves.

Plan A cost = .1x + 16
Plan A cost = .1(400) + 16
Plan A cost = 40 + 16
Plan A cost = $56

Plan B cost = .14x
Plan B cost = .14(400)
Plan B cost =  $56

Final answer: After 400 calls, Plan A and Plan B will both cost $56.