A certain telephone company offers two plans, A and B. Under plan A, the company charges a total of $0.60 for the first 5 minutes of each call and $0.06 per minute thereafter. Under plan B, the company charges $0.08 per minute of each call. What is the duration of a call, in minutes, for which the company charges the same amount under plan A and under plan B?	Pick
A) 2  B) 9  C) 15  D) 21  E) 30
Let the duration, in minutes, for which the company charges the same under plan A and plan B be t minutes.   Then under plan A the cost would be $0.6+0.06(t-5) and under plan B the cost would be $0.08t. We want these amount to be equal: 0.6+0.06(t-5)=0.08t --&gt; 60+6(t-5)=8t --&gt; t=15.   Answer: 15.
<result>C</result>
A certain telephone company offers two plans, A and B. Under plan A, the company charges a total of $0.60 for the first 5 minutes of each call and $0.06 per minute thereafter. Under plan B, the company charges $0.08 per minute of each call. What is the duration of a call, in minutes, for which the company charges the same amount under plan A and under plan B?