Subject: mathqa
Question: two cars are traveling in the same direction along the same route . the red car travels at a constant speed of 20 miles per hour , and the black car is traveling at a constant speed of 50 miles per hour . if the red car is 20 miles ahead of the black car , how many hours will it take the black car to overtake the red car ?
Option: 
A: 1.5
B: 1
C: 0.6
D: 0.1
Answer: C