Expand the numerator of a simplest fraction by 7 times to get 3. What is the simplest fraction?
把一个最简分数的分子扩大7倍，得3，这个最简分数是多少．
<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

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