Question

Two years of local phone service costs $607, including the installation fee of $55. What is the monthly fee?

Answer 1

`$23`

Explanation:

2 years + fee: `$607`

`607 - 55 = 552`

2 years: `$552`

1 year = 12 months

2 years = 24 months

24 months: `$552`

`2 = 24/12`

`23 = 552/24`

1 month: `$23`

Answer 2

See a solution process below:

Explanation:

The formula for the cost of local phone service is:

`c = (f * m) + i`

Where:

`c` is the total cost of the service: $607 for this problem.

`f` is the monthly fee: what we are solving for in this problem.

`m` is the number of months: Two years is 24 months for this problem.

`i` is the installation fee: $55 for this problem.

Substituting and solving for `f` gives:

`$607 = (f * 24) + $55`

`$607 - color(red)($55) = 24f + $55 - color(red)($55)`

`$552 = 24f + 0`

`$552 = 24f`

`($552)/color(red)(24) = (24f)/color(red)(24)`

`$23 = (color(red)(cancel(color(black)(24)))f)/cancel(color(red)(24))`

`$23 = f`

`f = $23`

The monthly fee would be $23.