There are several apples in a box, eat one-fifth of all the apples on the first day, and eat one-third of the remaining part on the second day, if you eat 20 more apples on the second day than the first day, ask the box How many apples are there?
一箱苹果有若干个，第一天吃了全部的五分之一，第二天吃去剩下部分的三分之一，如果第二天比第一天多吃了20个，问该箱苹果共有少个？
<gadget id="calculator">1 / 5</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 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(4/5) * (1/3)</gadget>
<output>4/15 = around 0.266667</output>

<gadget id="calculator">(4/15) - (1/5)</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">20 / (1/15)</gadget>
<output>300</output>

<result>300</result>