A fraction can be reduced to (1/4) if the numerator remains the same and the denominator is added by 2. If the denominator remains the same and the numerator is subtracted by 1, then they can be reduced to (2/9). What is this fraction?
一个分数如果分子不变，分母加2，那么可以化简为(1/4)，如果分母不变，分子减1，那么他们可以化简为(2/9)，这个分数是多少
<gadget id="calculator">5 / 18</gadget>
<output>5/18 = around 0.277778</output>

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