The numerator of a simplest fraction is enlarged by 4 times, and the denominator is reduced to (1/5) of the original number. After the simplification, the numerator is 1, and the denominator is the smallest composite number. What is the original simplest fraction?
一个最简分数的分子扩大4倍，分母缩小到原数的(1/5)，化简后分子是1，分母是最小的合数，原来的这个最简分数是多少．
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

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

<gadget id="calculator">(1/4) / 20</gadget>
<output>1/80 = around 0.0125</output>

<result>1/80 = around 0.0125</result>