Question

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

Answer 1

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.