The school library originally had 880 books, 100 of which were damaged and cleared out. Students donated another 120 books on Children's Day. How many books are there in the school?
学校图书室原有藏书880册，有100册破损清除了，六一儿童节时同学们又补捐了120册，学校现有图书多少册？
<gadget id="calculator">880 - 100</gadget>
<output>780</output>

<gadget id="calculator">780 + 120</gadget>
<output>900</output>

<result>900</result>