The form of the equation of the line is
[tex]y=mx+b[/tex]
where m is the slope and b is the y-intercept
In this case we will use
$170 for 3 hours as a point (3,170)
$220 for 5 hours as a pint (5,220)
First, we will use the next formula to find the slope of the line
[tex]m=\frac{y_2-y_1}{x_2-x_1}[/tex]
In this case
(3,170)=(x1,y1)
(5,220)=(x2,y2)
we substitute
[tex]m=\frac{220-170}{5-3}=\frac{50}{2}=25[/tex]
Then we calculate the the y-intercept using one point
[tex]170=25(3)+b[/tex][tex]b=170-75=95[/tex]
The equation is
[tex]y=25x+95[/tex]