Suppose a*b=3a-b*2, then 25*12=how much.
设a*b=3a-b*2，则25*12=多少．
<gadget id="calculator">25 * 3</gadget>
<output>75</output>

<gadget id="calculator">12 * 2</gadget>
<output>24</output>

<gadget id="calculator">75 - 24</gadget>
<output>51</output>

<result>51</result>