Given:
Flat fee = $12
Per minute charge = $0.05
Total bill for last month = $18
To find the number of minutes, we have the equation:
18 = 12 + 0.05M
Where M represents number of minutes
Let's solve for M:
Subtract 12 from both sides:
18 - 12 = 12 - 12 + 0.05M
6 = 0.05M
Divide both sides by 0.05:
[tex]\begin{gathered} \frac{6}{0.05}=\frac{0.05M}{0.05} \\ \\ 120\text{ = M} \end{gathered}[/tex]
Therefore, Marty spent 120 minutes talking on the phone last month.
ANSWER:
120 minutes
