In order to beautify the classrooms and purify the air, the school plans to buy some potted flowers. If 12 pots are placed in each classroom, 28 classrooms can be placed; if 16 pots are placed in each classroom, how many classrooms can be placed?
学校为了美化教室净化空气，准备购买一些盆花，如果每个教室放12盆，可以放28个教室；如果每个教室放16盆，可以放几个教室？
<gadget id="calculator">28 / 16</gadget>
<output>7/4 = around 1.75</output>

<gadget id="calculator">12 * (7/4)</gadget>
<output>21</output>

<result>21</result>