simple fraction, its numerator is reduced by 3 times and its denominator is enlarged by 5 times can be reduced to (2/7). What is the original fraction?
一个最简分数，它的分子缩小3倍，分母扩大5倍后可约成(2/7)，原分数是多少．
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">(2/7) * 5 * 3</gadget>
<output>30/7 = around 4.285714</output>

<result>30/7 = around 4.285714</result>