It is stipulated that "※" is a new operation. A※B=2A-B, then 3※4=how much.
规定"※"是一种新的运算．A※B=2A-B，那么3※4=多少．
<gadget id="calculator">2 * 3</gadget>
<output>6</output>

<gadget id="calculator">6 - 4</gadget>
<output>2</output>

<result>2</result>