Question

A phone company offers two monthly plans. Plan A costs $9 plus an additional $0.12 for each minute of calls . Plan B costs $15 plus an additional $0.07 for each minute of calls . For what amount of calling does the to plans cost the same ? What is the cost when the to plans cost the same ?

Answer 1

$23.40

Explanation:

We have to set up an equation for when A equals B.

Plan A = Plan B

x = # of additional minutes of calls

0.12x + 9 = 0.07x + 15

0.05x = 6

x = 120

Now we have the number of minutes needed. Since these 2 expressions are equal, you can just substitute 120 for either of them.

0.12x + 9 --> 0.12 (120) + 9 --> 23.4

Answer 2

Explanation:

Let x represent the number of minutes of call for which both plans would cost the same.

Plan A costs $9 plus an additional $0.12 for each minute of calls. This means that the total cost of using plan A for x minutes would be

9 + 0.12x

Plan B costs $15 plus an additional $0.07 for each minute of calls. This means that the total cost of using plan B for x minutes would be

15 + 0.07x

For both costs to be the same,

9 + 0.12x = 15 + 0.07x

0.12x - 0.07x = 15 - 9

0.05x = 6

x = 6/0.05 = 120 minutes

The cost when the two plans will cost the same is

15 + 0.07 × 120 = $23.4