Suppose a☆b=5a-3b is known X☆(3☆2)=18, then X=how much.
设a☆b=5a-3b已知X☆(3☆2)=18，那么X=多少．
<gadget id="calculator">5 * 3</gadget>
<output>15</output>

<gadget id="calculator">3 * 2</gadget>
<output>6</output>

<gadget id="calculator">15 - 6</gadget>
<output>9</output>

<result>9</result>