Question

A phone company charges a base fee of $12 per month plus an additional charge per minute. The monthly phone cost C can be represented by this equation: C=12+a.m, where a is the additional charge per minute, and m is the number of minutes used.

Which equation can be used to find the number of minutes a customer used if we know a and c

Answer 1

Real quick, we're going to turn the equation we were given into one that gives us M in terms of C and A.

We'll start with our original equation:

C = 12 + a * m

First, we'll move the 12 to the left side by subtracting it from both sides:

(C) - 12 = (12 + a * m) - 12

C - 12 = a * m

Next, we'll divide both sides by the a so all that will be left is m:

(C - 12) / a = (a * m) / a

(C - 12) / a = m

This means that option A is the correct choice!