Tom drove to the mountains last weekend. There was heavy traffic on the way there, and the trip took 9 hours. When Tom drove home, there was no traffic and the trip only took 4 hours. If his average rate was 40 miles per hour faster on the trip home, how far away does Tom live from the mountains?
Do not do any rounding.

Question

Tom drove to the mountains last weekend. There was heavy traffic on the way there, and the trip took 9 hours. When Tom drove home, there was no traffic and the trip only took 4 hours. If his average rate was 40 miles per hour faster on the trip home, how far away does Tom live from the mountains?
Do not do any rounding.

wolf1728 · Answer

distance = rate * time
distance = (r-40) * 9
distance = r * 4

distance = (r-40) * 9
distance = (9r-360) 

distance = r * 4
(9r-360) = r *4
5r -360 = 0
r = 72 mph

Trip to = 32 mph * 9 hours = 288 miles
Return Trip = 72 * 4 hours = 288 miles

So distance = 288 miles

Wow driving at 72 mph !! (That's somewhat over the extremely "fair" 55 mph speed limit.) LOL