If a*b=a*bb, try to find: (3*4)*6=how much.
如果a*b=a*b-b，试求：(3*4)*6=多少．
<gadget id="calculator">3 * 4</gadget>
<output>12</output>

<gadget id="calculator">12 - 4</gadget>
<output>8</output>

<gadget id="calculator">8 * 6</gadget>
<output>48</output>

<gadget id="calculator">48 - 6</gadget>
<output>42</output>

<result>42</result>