In a two-story bookshelf, the number of books on the upper floor is 3.5 times that of the lower floor. If 60 books are taken from the upper floor and placed in the lower floor, the number of books on the two floors is equal. How many books were placed on the upper floor?
一个两层的书架，上层放的书是下层的3.5倍，如果从上层取60本放入下层，则两层书的本数相等，上层原来放书多少本？
<gadget id="calculator">3.5 - 1</gadget>
<output>2.5</output>

<gadget id="calculator">2 / 2.5</gadget>
<output>0.8</output>

<gadget id="calculator">60 * 0.8</gadget>
<output>48</output>

<gadget id="calculator">48 * 3.5</gadget>
<output>168</output>

<result>168</result>