solving a distance, rate, time problem using a linear equation

Question

Aldo drove to the mountains last weekend. There was heavy traffic on the way there, and the trip took
8
hours. When Aldo drove home, there was no traffic and the trip only took
5
hours. If his average rate was
21
miles per hour faster on the trip home, how far away does Aldo live from the mountains?
Do not do any rounding.

Answer= ____ miles 

Answer 1

let distance=x

 

speed on coming back=x/5

speed on going=x/8

 

x/5-x/8=21

x=280 miles