During the "Science and Technology Month" activity, the school librarians lent out 369 science and technology books, leaving 215. How many science and technology books did the library have?
科技月"活动中，学校图书馆工借出科技数369本，还剩下215本．图书馆原有科技书多少本？
<gadget id="calculator">369 + 215</gadget>
<output>584</output>

<result>584</result>