The school bought 330 extra-curricular books, and later bought 120 more. Distribute these extracurricular books to 15 classes on average. How many books can each class get?
学校买来330本课外书，后来又买来120本．把这些课外书平均分给15个班，每个班能分到多少本？
<gadget id="calculator">330 + 120</gadget>
<output>450</output>

<gadget id="calculator">450 / 15</gadget>
<output>30</output>

<result>30</result>