The school established the "Love Library", and the students in the two classes of the fourth grade responded positively, donating an average of 15 books per person. There are 42 students in class one and 45 students in class two. How many books have been donated by the two classes?
学校成立了"爱心图书室"，四年级两个班的同学积极响应，平均每人捐献了15本书．一班有42名同学，二班有45名同学，两个班级一共捐献了多少本书？
<gadget id="calculator">42 + 45</gadget>
<output>87</output>

<gadget id="calculator">87 * 15</gadget>
<output>1_305</output>

<result>1_305</result>