A motorcycle traveling at 70 miles per hour overtakes a car

A motorcycle traveling at 70 miles per hour overtakes a car traveling at 40 miles per hour that had a three- hour head start. How far from the starting point are the two vechicles.

Solution

The car is 120 miles away when the motorcycle starts.
The bike gains on the car at 30 mph (70-40).
It take 4 hours for the bike to close the gap (120/30).
In 4 hours, the bike and the car are 280 miles from the starting point.
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4*70 = 280
7*40 = 280