Question

A cell phone plan charges $39.95 a month plus 15 cents per text message sent and 15 cents per message received. Using s to represent the number of text messages sent in one month and r to represent the number of text messages received in one month, the following equation can be used to calculate the total monthly cost, c.

C=39.95+.15(s+r)
If it is known that the total monthly cost is $53.45 and 63 text messages were received, solve for s, the total number of text messages sent.

Answer 1

The total number of text messages sent was 27.

Explanation:

The monthly cost of the cell phone plan, in function of the number of text messages sent(s) and the number of messages received(r), is given by:

`C = 39.95 + 0.15(s + r)`

In this question, we have that:

`C = 53.45, r = 63`

We put this into the equation to find the value of s. So

`C = 39.95 + 0.15(s + r)`

`53.45 = 39.95 + 0.15(s + 63)`

`0.15s + 9.45 = 13.50`

`s = (13.50 - 9.45)/(0.15)`

`s = 27`

The total number of text messages sent was 27.