The students participate in the chess competition. There are 18 students in the middle grades and 22 students in the senior grades. Every 4 students are divided into groups. How many groups can be formed?
同学们参加象棋比赛，中年级有18人参加，高年级有22人参加，每4人分成一组，可以成几组？
<gadget id="calculator">18 + 22</gadget>
<output>40</output>

<gadget id="calculator">40 / 4</gadget>
<output>10</output>

<result>10</result>