A fraction, if the numerator remains unchanged and the denominator is added by 2, then it can be reduced to (1/4); if the denominator remains unchanged and the numerator is reduced by 1, then it can be reduced to (2/9), what is the fraction.
一个分数，如果分子不变，分母加2，那么可以约简为(1/4)；如果分母不变，分子减1，那么把它化简是(2/9)，这个分数是多少．
<gadget id="calculator">20 - 2</gadget>
<output>18</output>

<gadget id="calculator">5 / 18</gadget>
<output>5/18 = around 0.277778</output>

<result>5/18 = around 0.277778</result>