The distance an object travels is determined by how fast it goes and for how long it moves. If an object's speed
 remains constant, the formula is d=rt, where d is the distance, r is the speed, and t is the time.
 If you drive at 50 miles per hour for 5 hours, how far will you have traveled?
 a. 200 miles
 b. 10 miles
 c. 250 miles
 d.300 miles