Question 887930
Two cyclists start biking from a trailhead at different speeds and times. The second cyclist travels at 10 miles per hour and starts 2 hours after the first cyclist, who is traveling at 6 miles per hour. Once the second cyclist starts biking, how much time will pass before he catches up with the first cyclist? 
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In 2 hours, the 1st cyclist is 12 miles away (2*6).
The 2nd cyclist "gains on" the 1st are 4 mi/hr (10-6).
12/4 = 3 hours.