word problem

Question

Jon recently drove to visit his parents who live 600 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 25 hours driving, find the two rates.

Answer 1

Let's denote (the average) speed to,  as v. Then (the average) speed from,  will be v-14. Average speed in both ways is 2v-14 and 

2v-14=2s/25, where s = 600 miles (distance)

2v=14+1200/25

v=7+600/25

v=7+24=31

So the average speed there was 31mph and back 17mph (=31-14).