There is a bookshelf, if 15 books are taken from the first floor and placed on the second floor, then the number of books on the second floor is exactly the number of books on the first floor (5/7). It is known that there were originally 35 books on the second floor. How many books are there on the first floor and the second floor?
有一个书架，如果从第一层里拿出15本放到第二层，这时第二层里的书的本数正好是第一层的(5/7)．已知第二层原来有书35本，原来第一层和第二层共有书多少本？
<gadget id="calculator">35 + 15</gadget>
<output>50</output>

<gadget id="calculator">5 / 7</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">50 / (5/7)</gadget>
<output>70</output>

<gadget id="calculator">70 + 50</gadget>
<output>120</output>

<result>120</result>