A fraction is (2/5) after simplification. Add 8 to the denominator, and the fraction value is (2/7). What is the original fraction?
一个分数化简后是(2/5)，分母加上8，分数值就是(2/7)，原分数是多少．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<result>2/5 = around 0.4</result>