John buys a box of 40 light bulbs.  He uses 16 of them and then gives half of what is left to a friend.  How many does he have left?
He had 40-16=
<gadget id="calculator">40-16</gadget>
<output>24</output>
24 left after using some.
Then after giving some away he is left with 24/2=
<gadget id="calculator">24/2</gadget>
<output>12</output>
12.

<result>12</result>