There are 21 boys and 15 girls in Class 3 and 2 of Dongfeng Primary School. Every 4 people are divided into a group, how many groups can be divided into?
东风小学三2班有男生21人，女生15人．每4人分成一个小组，可以分成几个小组？
<gadget id="calculator">21 + 15</gadget>
<output>36</output>

<gadget id="calculator">36 / 4</gadget>
<output>9</output>

<result>9</result>