Bobby wanted pancakes for breakfast.  The recipe on the box makes 21 pancakes.  While he ate 5 pancakes, his dog jumped up and was able to eat 7 before being caught.  How many pancakes does Bobby have left?
Bobby ate 5 pancakes and his dog ate 7 so 5+7 = 
<gadget id="calculator">5+7</gadget>
<output>12</output>
12.
The recipe makes 21 pancakes and 12 were eaten so 21-12 = 
<gadget id="calculator">21-12</gadget>
<output>9</output>
9 pancakes were left.

<result>9</result>