There are two bookshelves, A and B. Bookshelf A has 600 books, borrowed from A bookshelf (1/3), after borrowing 75% from B bookshelf, the books on A bookshelf are twice as many as the books on B bookshelf 150 books, how many books are there on shelf B? (column solution)
甲，乙两个书架，甲书架有书600本，从甲书架借出(1/3)，从乙书架借出75%以后，甲书架上的书比乙书架上的书的2倍还多150本，乙书架原有书多少本？(列式解答)
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 - (1/3)</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">600 * (2/3)</gadget>
<output>400</output>

<gadget id="calculator">400 - 150</gadget>
<output>250</output>

<gadget id="calculator">75 / 100</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 - (3/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">250 / 2 / (1/4)</gadget>
<output>500</output>

<result>500</result>