Luke had 20 stickers. He bought 12 stickers from a store in the mall and got 20 stickers for his birthday. Then Luke gave 5 of the stickers to his sister and used 8 to decorate a greeting card. How many stickers does Luke have left?
<gadget id="calculator">20 + 12</gadget>
<output>32</output>

<gadget id="calculator">32 + 20</gadget>
<output>52</output>

<gadget id="calculator">52 - 5</gadget>
<output>47</output>

<gadget id="calculator">47 - 8</gadget>
<output>39</output>

<result>39</result>