There are 12 volleyballs in the sports room, and the number of footballs is three times that of volleyballs. How many fewer volleyballs are there than footballs?
体育室有排球12只，足球的只数是排球的3倍．排球比足球少多少只？
<gadget id="calculator">12 * 3</gadget>
<output>36</output>

<gadget id="calculator">36 - 12</gadget>
<output>24</output>

<result>24</result>