Question 813851
Garrett averages 60 mph and Gordon averages 65 mph. Gordon couldn't find his car keys, so he lest the office to travel to a meeting in another state 15 minutes after Garrett. How long will it be until Gordon catches up to Garrett? 
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In 15 minutes, Garrett is 15 miles away (60 mi/hr * 1/4 hr)
Gordon "gains on him" at 5 mi/hr (65-60)
15/5 = 3 hours to catch up.
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Gordon "gains on him" at 5 mi/hr (65-60)
Gordon's speed with respect to Garrett is 5 mi/hr = "gains on"