Answer: 20
Reason:
The equation is in y = mx+b form where
m = 20 = slope
b = 0 = y intercept
The slope is the rate of change. It tells us how fast y increases.
slope = rise/run = 20 = 20/1
rise = 20 = increase the earnings by 20 dollars
run = 1 = each time the number of hours go up by 1