The school bought 1,400 books and distributed them to each class on average. Each class has 50 books, and there are 150 books left. How many classes are there in the school?
学校买来1400本图书，平均分给各个班级，每班50本，还剩下150本，学校一共有多少个班？
<gadget id="calculator">1_400 - 150</gadget>
<output>1_250</output>

<gadget id="calculator">1_250 / 50</gadget>
<output>25</output>

<result>25</result>