If the cost of a call is 5.39, obviously this person stayed more than one minute at the telephone. It will pay for:
- 2.74 for service charge;
- 0.91 for the first minute;
- x for the additional minutes.
If we will find out the value of x, we will know how much time this person paid for additional minutes. Let's make some subtractions:
- The total minus the service charge:
;
- 2.65 minus the first minute:
So, this person paid 1.74 by additional minutes. Let's divide this value by the price for additional minute:
This means that it paid by 3 minutes additional.
Therefore, this people stayed at telephone by 3 + 1 = 4 minutes.