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=
<gadget id="calculator">15/60</gadget>
<output>1/4 = around 0.25</output>
.25 hour head start.
That means it ran 20*.25=
<gadget id="calculator">20*.25</gadget>
<output>5</output>
5 miles.
The rabbit goes 25-20=
<gadget id="calculator">25-20</gadget>
<output>5</output>
5 mph faster than the cat.
So it takes 5/5=
<gadget id="calculator">5/5</gadget>
<output>1</output>
1 hour for the rabbit to catch up.

<result>1</result>