There are two bookshelves, 25% of the books stored in shelf A are equivalent to (2/3) of the books stored in shelf B, and shelf A stores 120 more books than shelf B. How many books are stored on shelf B?
两个书架，甲书架存书的25%相当于乙书架存书的(2/3)，甲书架比乙书架多存120本．乙书架存书多少本？
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

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

<gadget id="calculator">(2/3) / (1/4)</gadget>
<output>8/3 = around 2.666667</output>

<gadget id="calculator">(8/3) - 1</gadget>
<output>5/3 = around 1.666667</output>

<gadget id="calculator">120 / (5/3)</gadget>
<output>72</output>

<result>72</result>