Jerry drove from St. Louis, MO to Kansas City, MO in 5.5 hours. On the return trip he decided to increase his speed by 15 mph and the return took 4.5 hours. Find the rate on the return trip. What is the distance from St. Louis to Kansas City?

let x - speed of return trip

5.5 hours (x -15)  = 4.5 hours (x)

5.5x  - 82.5 = 4.5x

5.5x - 4.5x = 82.5

x = 82.5 mph 

distance = 82.5 mph x 4.5 hours = 371.25 miles