Add 18 to the numerator and 42 to the denominator of a simplest true fraction, and the fraction remains the same. What is the original fraction?
一个最简真分数的分子加上18，分母加上42，分数大小不变，原来的分数是多少．
<gadget id="calculator">18 / 42</gadget>
<output>3/7 = around 0.428571</output>

<result>3/7 = around 0.428571</result>