If "a△b=(ab)*3", then 7△(3△2)=how much.
如果"a△b=(a-b)*3"，那么7△(3△2)=多少．
<gadget id="calculator">3 - 2</gadget>
<output>1</output>

<gadget id="calculator">1 * 3</gadget>
<output>3</output>

<gadget id="calculator">7 - 3</gadget>
<output>4</output>

<gadget id="calculator">4 * 3</gadget>
<output>12</output>

<result>12</result>