Tom's ship can travel at 10 miles per hour.  He is sailing from 1 to 4 PM.  He then travels back at a rate of 6 mph.  How long does it take him to get back?
He was travelling at full speed for 4-1=
<gadget id="calculator">4-1</gadget>
<output>3</output>
3 hours.
So he went 3*10=
<gadget id="calculator">3*10</gadget>
<output>30</output>
30 miles.
That means it takes 30/6=
<gadget id="calculator">30/6</gadget>
<output>5</output>
5 hours to get back.

<result>5</result>