Question

A telephone plan consists of a monthly fee of $15 plus 20 cents per minute for long distance calls are made. Write an equation for the total monthly cost C, when n minutes are used for long distance calls.

Answer 1

a)Using the given information we can set the following equation:

$C=0.20n+15$

b) The graph of the linear equation above for up to and including 200 minutes is as follows:

Which corresponds to option B.

c) If n=40 then:

$C=0.20\cdot40+15=8+15=23$

Then the total monthly cost is $23.

d) If C=30, solving the first equation on the board for n we get:

$\begin{gathered} 30=0.20n+15 \\ 0.20n=15 \\ n=75 \end{gathered}$

Then the number of minutes is 75.