Aphone 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?

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