Jack orders 3 sandwiches that cost $5 each.  He pays with a $20 bill.  How much does he get in change?
The cost was 3*5=$
<gadget id="calculator">3*5</gadget>
<output>15</output>
15.
So he got 20-15=$
<gadget id="calculator">20-15</gadget>
<output>5</output>
5 in change.

<result>5</result>