There are 1,300 seats in the cinema, and there are 28 classes in the school, with an average of 45 students in each class. How many seats are vacant?
电影院里有1300个座位，学校有28个班，平均每个班有45人，有多少个座位空着？
<gadget id="calculator">28 * 45</gadget>
<output>1_260</output>

<gadget id="calculator">1_300 - 1_260</gadget>
<output>40</output>

<result>40</result>