Question

A phone company offers two monthly charge plans. In Plan A, there is no monthly fee, but the customer pays 9 cents per minute of use. In Plan B, the customerpays a monthly fee of $8.60 and then an additional 7 cents per minute of use.For what amounts of monthly phone use will Plan A cost at least as much as Plan B?Use m for the number of minutes of phone use in a month, and solve your inequality for m.

Answer 1

Where c is the cost and m is the number of minutes of phone use in a month

Plan A;

c = 9m

Plan B;

c = 8.6 + 7m

The amounts of monthly phone use that will make Plan A cost be at least as much as Plan B.

`\begin{gathered} \text{Plan A }\ge\text{ Plan B} \\ 9m\text{ }\ge\text{ 8.6 + 7m} \\ 9m\text{ - 7m }\ge8.6 \\ 2m\text{ }\ge\text{ 8.6} \\ m\text{ }\ge\text{ }(8.6)/(2) \\ \\ m\text{ }\ge\text{ 4.3 minutes} \end{gathered}`