A truck leaves a location traveling due east at a constant speed of 50 miles per hour. One hour later a car leaves the same location traveling in the same direction at a constant speed of 70 miles. If both vehicles continue in the same direction at their same respective speeds, how many hours will it take the car to catch up to the truck?

GMAT Problem-solving questions consist of topics such as arithmetic, algebra, geometry, and more. 
Approximately 18 – 20 questions are there.