There are 800 books on shelf A, and 240 books on shelf B. Now both shelves A and B have taken away the same amount of books. The remaining books on shelf B are exactly 1/5 of the books on shelf A. Bookshelves A and B are taken away respectively. How many books did you buy?
甲书架有800本书，乙书架有240本书，现在甲乙两书架分别都取走相等的书，乙书架剩下的书正好是甲书架的(1/5)，甲、乙书架分别取走了多少本书？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">800 * (1/5)</gadget>
<output>160</output>

<gadget id="calculator">240 - 160</gadget>
<output>80</output>

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

<gadget id="calculator">80 / (4/5)</gadget>
<output>100</output>

<result>100</result>