Subtract a number from the numerator and denominator of the fraction (85/157) and divide the result into (2/5), what is the subtracted number?
分数(85/157)的分子、分母同时减去一个数字，将结果约分得(2/5)，则减去的数字是多少．
<gadget id="calculator">157 - 120</gadget>
<output>37</output>

<result>37</result>