There are 24 boxes of chess in the activity room, the number of boxes of military chess is twice that of chess, and there are 12 boxes of checkers, how many boxes of checkers are less than military chess.
活动室有24盒象棋，军棋的盒数是象棋的2倍，跳棋有12盒，跳棋比军棋少多少盒．
<gadget id="calculator">24 * 2</gadget>
<output>48</output>

<gadget id="calculator">48 - 12</gadget>
<output>36</output>

<result>36</result>