There are 120 books in the bookshelves A and B. Later, 15 books are taken out from the A bookshelf and placed in the B bookshelf. At this time, there are the same number of books on the two bookshelves. How many books are there in the A bookshelf?
甲乙两书架共有120本书，后来从甲书架取出15本放入乙书架，这时两个书架上的本数同样多，甲书架原有多少本书？
<gadget id="calculator">15 * 2</gadget>
<output>30</output>

<gadget id="calculator">120 + 30</gadget>
<output>150</output>

<gadget id="calculator">150 / 2</gadget>
<output>75</output>

<result>75</result>