Question

Customers of a phone company can choose between two service plans for long distance calls. The first plan has a $19 monthly fee and charges an additional $0.11 for each minute of calls. The second plan has an $11 monthly fee and charges an additional $0.15 for each minute of calls. For how many minutes of calls will the costs of the two plans be equal?

Answer 1

200 minutes

Explanation:

The first plan:

`A=0.11m+19`

The second plan:

`B=0.15m+11`

To find the point where the plans are equal in cost, set them equal and solve for
`m`:

`0.11m+19=0.15m+11`

`0.11m+19-11=0.15m`

`19-11=0.15m-0.11m`

`8=0.04m`

`200=m`

Therefore, at 200 minutes, both calling plans are equal in cost. To verify, we substitute 200 for
`m` in each formula and check that they are equal:

`A=0.11m+19`

`A=0.11(200)+19`

`A=22+19=41`

`B=0.15m+11`

`B=0.15(200)+11`

`B=30+11=41`