Suppose a*b=3a-2b, x*(4*1)=7, then what is the value of x*4
假设a*b=3a-2b，x*(4*1)=7，那么x*4的值是多少
<gadget id="calculator">9 * 3</gadget>
<output>27</output>

<gadget id="calculator">2 * 4</gadget>
<output>8</output>

<gadget id="calculator">27 - 8</gadget>
<output>19</output>

<result>19</result>