Tom needs to lower a rope down 6 stories.   One story is 10 feet.  The only rope being sold is 20 feet long but you lose 25% when lashing them together.  How many pieces of rope will he need to buy?
He needs 10*6=
<gadget id="calculator">10*6</gadget>
<output>60</output>
60 feet.
He loses 20*.25=
<gadget id="calculator">20*.25</gadget>
<output>5</output>
5 feet each time.
So he gets 20-5=
<gadget id="calculator">20-5</gadget>
<output>15</output>
15 feet from each piece.
That means he needs 60/15=
<gadget id="calculator">60/15</gadget>
<output>4</output>
4 pieces of rope.

<result>4</result>