For a simplest fraction, the numerator is expanded to 5 times the original, the denominator is reduced to the original (1/5), and the fraction is (13/4). What is the original fraction?
一个最简分数，分子扩大到原来的5倍，分母缩小到原来的(1/5)，约分后得(13/4)，原来这个分数是多少？
<gadget id="calculator">13 / 5</gadget>
<output>13/5 = around 2.6</output>

<gadget id="calculator">4 * 5</gadget>
<output>20</output>

<gadget id="calculator">(13/5) / 20</gadget>
<output>13/100 = around 0.13</output>

<result>13/100 = around 0.13</result>