Answer:
The answer is 8
Step-by-step explanation:
Lets consider that Sam's call will last x minutes in total. Then, equations for cost will be as follows:
A Pay Phone Cost: [tex]p(x)=1+0,5*x[/tex]
Operator Cost: [tex]o(x)=3+0,25*x[/tex]
If we make both costs equal, the equation will be:
[tex]1+0,5*x=3+0,25*x\\0,25*x=2\\x=8[/tex]
Sam's call need to last 8 minutes to make payphone cost and operator cost same.