There are two layers of books on the bookshelf, and there are 50 books on the upper layer. After taking out (1/5) of them and putting them in the lower layer, there are as many books on the upper and lower layers. How many books are there in total on the bookshelf?
书架上有两层书，上层有50本，拿出其中的(1/5)放入下层后，上下两层一样多，书架上共有书多少本？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">50 * (1/5)</gadget>
<output>10</output>

<gadget id="calculator">(1/5) * 50</gadget>
<output>10</output>

<gadget id="calculator">50 - 10 - 10</gadget>
<output>30</output>

<gadget id="calculator">30 + 50</gadget>
<output>80</output>

<result>80</result>