Define the operation "※"; a※b=(a*b)-(a+b), then 2※(3※4)=how much.
定义运算"※"；a※b=(a*b)-(a+b)，则2※(3※4)=多少．
<gadget id="calculator">3 * 4</gadget>
<output>12</output>

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

<gadget id="calculator">12 - 7</gadget>
<output>5</output>

<gadget id="calculator">2 * 5</gadget>
<output>10</output>

<gadget id="calculator">2 + 5</gadget>
<output>7</output>

<gadget id="calculator">10 - 7</gadget>
<output>3</output>

<result>3</result>