There is a box of 50 bottles of Sprite. After selling 20% of it, it is filled with 20% of the remaining Sprite in the box. How many bottles are loaded?
有一箱50瓶装的雪碧，卖出它的20%后，又装入箱子里所剩雪碧的20%，装入多少瓶．
<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">50 * (4/5) * (1/5)</gadget>
<output>8</output>

<result>8</result>