total of 12 students in grades three, four, and five are doing exercises. There are 20 people standing in each row, exactly 27 rows, how many people are there on average in each class?
三、四、五年级共12个班级学生在做操．每行站20人，正好站27行，平均每个班级有多少人？
<gadget id="calculator">27 / 12</gadget>
<output>9/4 = around 2.25</output>

<gadget id="calculator">20 * (9/4)</gadget>
<output>45</output>

<result>45</result>