fraction is rounded once with 2 and once with 3, and (2/5) is obtained. What is the fraction before the rounding?
一个分数用2约了一次，用3约了一次，得到(2/5)，则约分前的分数是多少．
<gadget id="calculator">5 * 2 * 3</gadget>
<output>30</output>

<gadget id="calculator">3 / 30</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">2 * 2 * (1/10)</gadget>
<output>2/5 = around 0.4</output>

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