There are some potted flowers planted in the school flower room. If 3 pots are placed in each classroom, 28 classrooms can be placed. How many classrooms can be placed if there are 4 pots in each classroom?
学校花房里栽了一些盆花．如果每间教室放3盆，可以放28个教室．如果每间教室放4盆，可以放多少间教室？
<gadget id="calculator">28 / 4</gadget>
<output>7</output>

<gadget id="calculator">3 * 7</gadget>
<output>21</output>

<result>21</result>