Question

Brock is a plumber. He charges a flat rate of $40 to visit a house to inspect its plumbing. He charges an additional $20 for every hour he spends inspecting or making repairs which graph below correctly shows the price of using brocks plumbing service vs time?

A) graph W
B) graph X
C) graph Y
D) graph Z

Answer 1

Let x =  hours of service.
Let y = total charges for x hours
The fixed charge is $20.
The charge per hour is $20.

Brock's charges for x hours is
y = 40 + 20x

This is a straight line with slope = 20 and y-intercept = 40.
The correct graph is W.

Answer: W