There are two bookshelves. (1/4) of books stored in shelf A is equal to (2/5) of books stored in shelf B. 120 more books are stored in shelf A than shelf B. How many books are stored in shelf B?
两个书架，甲架存书的(1/4)等于乙架存书的(2/5)，甲架比乙架多存书120本，乙架存书多少本？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(2/5) / (1/4)</gadget>
<output>8/5 = around 1.6</output>

<gadget id="calculator">(8/5) - 1</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">120 / (3/5)</gadget>
<output>200</output>

<result>200</result>