Tom's rabbit can run at 25 miles per hour.  His cat can run 20 miles per hour.  The cat gets a 15-minute head start.  In hours, how long will it take for the rabbit to catch up?
The cat got a 15/60=<<15/60=.25>>.25 hour head start
That means it ran 20*.25=<<20*.25=5>>5 miles
The rabbit goes 25-20=<<25-20=5>>5 mph faster than the cat
So it takes 5/5=<<5/5=1>>1 hour for the rabbit to catch up
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