Xiaojun read a 120-page story book and read 20% of it in 4 days. According to this calculation, how many days will it take to finish reading the remaining pages? (Solve it in two ways, one of which is a proportional solution)
小军读一本120页的故事书，4天读了20%．照这样计算，剩下的页数还要几天读完？(用两种方法解，其中一种用比例解)
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">(1/5) / 4</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(4/5) / (1/20)</gadget>
<output>16</output>

<result>16</result>