It is stipulated that lucky is counted as a※b=2ab-4, then (3※4)※5=how much.
规定幸运算a※b=2ab-4，那么(3※4)※5=多少．
<gadget id="calculator">2 * 3 * 4</gadget>
<output>24</output>

<gadget id="calculator">24 - 4</gadget>
<output>20</output>

<gadget id="calculator">2 * 20 * 5</gadget>
<output>200</output>

<gadget id="calculator">200 - 4</gadget>
<output>196</output>

<result>196</result>