Subtract 20 from the denominator of the fraction (16/40), how much should the numerator be divided to keep the size of the fraction constant
分数(16/40)的分母减去20，要使分数的大小不变，分子应除以多少
<gadget id="calculator">40 - 20</gadget>
<output>20</output>

<gadget id="calculator">40 / 20</gadget>
<output>2</output>

<result>2</result>