A*(2/5)=B*(5/6), known A=50, B=how many.
A*(2/5)=B*(5/6)，已知A=50，B=多少．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">50 * (2/5)</gadget>
<output>20</output>

<gadget id="calculator">6 / 5</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">20 * (6/5)</gadget>
<output>24</output>

<result>24</result>