Car A leaves Los Angeles at noon driving North to San Franci

Car A leaves Los Angeles at noon driving North to San Francisco at 60 mph. Car B leaves at 1 pm traveling the same route at 70 mph. How many hours after car B leaves will it catch up with car A?

car A has a 60 mi head start

car B is going 10 mph faster

it takes car B 6 hr (60mi / 10mph) to catch up