Solving simple equations: If we stipulate: a☆b=a+2b, then the solution of the equation x☆2=3☆(2☆3).
解简易方程：如果我们规定：a☆b=a+2b，则方程x☆2=3☆(2☆3)的解．
<gadget id="calculator">3 * 2</gadget>
<output>6</output>

<gadget id="calculator">2 + 6</gadget>
<output>8</output>

<gadget id="calculator">8 * 2</gadget>
<output>16</output>

<gadget id="calculator">3 + 16</gadget>
<output>19</output>

<gadget id="calculator">2 * 2</gadget>
<output>4</output>

<gadget id="calculator">19 - 4</gadget>
<output>15</output>

<result>15</result>