Awashing 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.

In all honesty, there really is no “work” per say to show. mainly it’s just using the process of elimination. the question is asking which domain(s) would be the most appropriate for the function c(n). n is the number of observed vehicles so right away, 1, 2, and 3 can be eliminated.why? 1, 2 start in the negatives and therefore it is impossible to observe negative cars. so, #4 would be the best answer to the given problem.