Peter is an artist, and he charges for his paintings on an hourly basis. He also receives tips from many of his clients. The scatter plot below shows the number of hours Peter
worked on a painting and the amount of money he received from his client. A line of
best fit for these data points, the equation y=85x+20, is also shown on the plot.
Amount Paid vs. Hours Worked
300+
400+
300+
Amount Paid (dollars
200+
100+
S
6
3 4
Hours Worked
On average, how many more dollars does a client pay for a painting that takes 4 hours
than a painting that takes 3 hours?