The school bought 320 exercise books and distributed them to 5 classes in the third grade. On average, each class got 47 books. How many books are left?
学校买了320本练习本，分给三年级5个班，平均每个班分得47本，还剩多少本？
<gadget id="calculator">47 * 5</gadget>
<output>235</output>

<gadget id="calculator">320 - 235</gadget>
<output>85</output>

<result>85</result>