Question

Jon recently drove to visit his parents who live 528 miles away. On his way there his average speed was 14 miles per hour faster than on his way home (he ran into some bad weather). If Jon spent a total of 22 hours driving, find the two rates.

Answer 1

speed while going = 42, while returning home = 28

Explanation:

let his speed on the way to his parents house is (x)

then his speed while returning is x - 14

Time = Distance / speed

528 / x + 528 / x -14 = 22

multiplying the denominator ...

528x + 528x +7392 = 22x^2 +14x

1056x + 7392 = 22x^2 + 308x

0 = 22x^2 -748x -7392

"dividing by 22"

0 = x^2 -34x-336

0 = (x+8) (x-42)

x must be 42

finally jon's speed while back home is 42 - 14 = 28