Answer:
20 ; $135 ; service charge for 3 hours spent is $135
Explanation:
Given that :
Service fee equation model :
C(h)= 75 + 20h
C = total cost of the service call
h = number of hours the plumber spends working on the problem
The charge per hour is the gradient or slope of the linear equation. From the equation, the slope is of the equation is related to bx from. The general form of a linear equation where b = gradient or slope(charge per hour) and x = number of hours
bx = 20h
b = 20
Charge per hour = 20
C(3) = 75 + 20(3)
75 + 60 = 135
This means that total service call charge for a plumber who spends three hours fixing a problem is $135