How do you write an equation of each line i. slope- intercept form? i’m really confused.

The slope intercept form is y = mx + b

Where m is the slope and b is the y-intercept.

From the graph, the y-intercept is on point (0,20), so b = 20

To find the slope, find two points that fall perfectly on the line.  The two points I see are (0,20) and (2,80).  

To find the slope, solve:  (80-20)/(2-0) = 60/2 = 30
So m = 30

So we have our equation:  y = 30x +20

If i'm correct the answer is $15.97