A bookshelf has upper and lower floors. The ratio of the number of books on the upper and lower floors is 5:6. After taking 5 books from the upper floor and placing them in the lower floor, the number of books on the upper floor is less than that on the lower floor (3/7). How many books are there in total on the bookshelf?
一个书架有上、下两层，上下层书的本数的比是5：6，从上层拿5本放入下层后，上层的书比下层少(3/7)，书架上共有多少本书？
<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">(3/7) * 5</gadget>
<output>15/7 = around 2.142857</output>

<gadget id="calculator">5 - (15/7)</gadget>
<output>20/7 = around 2.857143</output>

<gadget id="calculator">5 + (20/7)</gadget>
<output>55/7 = around 7.857143</output>

<gadget id="calculator">5 / 11</gadget>
<output>5/11 = around 0.454545</output>

<gadget id="calculator">6 / 11</gadget>
<output>6/11 = around 0.545455</output>

<gadget id="calculator">(3/7) * (6/11)</gadget>
<output>18/77 = around 0.233766</output>

<gadget id="calculator">(18/77) - (6/11)</gadget>
<output>-24/77 = around -0.311688</output>

<gadget id="calculator">(5/11) + (-24/77)</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">(55/7) / (1/7)</gadget>
<output>55</output>

<result>55</result>