It is stipulated that "△" is a new operation, A△B means 2A-B, such as 4△3=4*2-3=5, then 9△6=how much.
规定"△"是一种新运算，A△B表示2A-B，如4△3=4*2-3=5，那么9△6=多少．
<gadget id="calculator">9 * 2</gadget>
<output>18</output>

<gadget id="calculator">18 - 6</gadget>
<output>12</output>

<result>12</result>