The books on shelf A belong to shelf B (5/8). If you take 20 books from shelf B and put them into shelf A, then the books on the two shelves are equal. How many books are there in shelf B?
甲书架的书是乙书架的(5/8)，如果从乙书架拿20本放入甲书架，则两个书架书相等，乙书架原有多少本？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">7 + 5</gadget>
<output>12</output>

<gadget id="calculator">5 / 12</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">(1/2) - (5/12)</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">20 / (1/12)</gadget>
<output>240</output>

<gadget id="calculator">7 / 12</gadget>
<output>7/12 = around 0.583333</output>

<gadget id="calculator">240 * (7/12)</gadget>
<output>140</output>

<result>140</result>