For a simple fraction, if its numerator is enlarged by 3 times and its denominator is reduced by 2 times, the result is 2 (4/13), what is the original fraction?
一个最简分数，把它的分子扩大3倍，分母缩小2倍后得数是2(4/13)，原分数是多少．
<gadget id="calculator">30 / 3</gadget>
<output>10</output>

<gadget id="calculator">13 * 2</gadget>
<output>26</output>

<gadget id="calculator">10 / 26</gadget>
<output>5/13 = around 0.384615</output>

<result>5/13 = around 0.384615</result>