A fraction, if it is reduced to the simplest fraction, the result is (2/3); if the numerator of this fraction is added with 4, and then reduced to the simplest fraction, the result is (4/5). So what is the original score.
一个分数，若把它化为最简分数，结果是(2/3)；若把这个分数的分子加上4，再化成最简分数，则结果为(4/5)．那么原来的分数是多少．
<gadget id="calculator">20 / 30</gadget>
<output>2/3 = around 0.666667</output>

<result>2/3 = around 0.666667</result>