Question

A plumber charges $60 for a service call, plus $40 per hour for any work completed. Which graph below shows the total amount the plumber charges, c, for a service call and h hours of work?

Answer 1

using slope intercept equation

$\begin{gathered} y=mx+b \\ \text{where} \\ m=\text{slope} \\ b=y-\text{intercept} \end{gathered}$

Therefore, the equation is

$\begin{gathered} y=60+40x \\ x=\text{hour of work} \\ y=\text{charges in dollars} \\ y=40x+60 \end{gathered}$

let us test the x values to know the graph

$\begin{gathered} y=40x+60 \\ y=40(1)+60=100 \\ y=40(2)+60=140 \\ y=40(3)+60=180 \\ y=40(4)+60=220 \\ y=40(5)+60=260 \\ y=40(6)+60=300 \end{gathered}$

The answer is B