It is stipulated that a*b=2a+b, then (2*3)*4=how much.
规定a*b=2a+b，则(2*3)*4=多少．
<gadget id="calculator">7 * 2</gadget>
<output>14</output>

<gadget id="calculator">14 + 4</gadget>
<output>18</output>

<result>18</result>