A washing machine repair man charges a fixed fee of $50 plus $12 per hour. If the total charge for a job was $115, the number of minutes spent on the job was

a) 250

b) 300

c) 325

d) 380

e) 315

Fixed Charge FC = $50

$12 per hour.

Let number of hours = n

Total Charge TC = 50 + 12n

For a total charge of $115.

50 + 12n = 115

12n = 115 - 50

12n = 65

n = 65/12

n = (65/12) hours.

Number of minutes = (65/12) * 60, since 1 hour = 60 minutes

= 65*5 = 325 minutes

Option C.