C=3.12 + .18x, where C= total cost per month and x= total number of minutes used in one month. For a month where 175 minutes are used, the total cost would be $34.62.
Work Step by Step
For this cell phone plan, there is a constant, monthly fee of 3.12 dollars. In order to find the total cost for one month, one must add 3.12 to the total cost for the number of minutes used. To find the total cost of minutes used, you must multiply the rate, .18, by the number of minutes used. Therefore, the total cost for one month would be 3.12+.18x, where x=the number of minutes used in one month.