A $45 pair of shoes is on sale for 20% off. How much money is saved?

Horace's speedometer reads 60 miles per hour, but during a road test he finds that he was actually driving 58 mph. what is the percent error in horaces speedometer?

The circumference of a circle is 5 pi cm. what is the area of the circle?

Iam trying to solve a linear equation for the shoe size of someone 84" tall taking into consideration example 1 is 69" tall with a shoe size of 9 and example 2 is 72 inches tall with a shoe size of 11. i understand that the equation should be y=mx+b and that on the graph the answer is (3,2) but i just don't understand how to create the equation to solve for 84-inches and 60-inches tall questions. after two days, i need .