Question 5754
First step I did was find the convert to inches the diameter of the track.

76 * 12 = 912

Next, find the length of the track.

3.14 * 912 = 2865

Next, divide the distance by the number of revolutions of the wheel.

59.7

This is the distance traveled by one revolution of the wheel.

This distance = pi * the diameter of the wheel.

59.7 / pi = 19 inches for the diameter of the wheel.

The reason they multiplied by 12 is to have the calculations of the equation put into  inches instead of feet.