On March 12th, Arbor Day, teachers and students of Shengli Primary School participated in the tree planting activity. Every 4 people were divided into groups, and each group planted 8 trees. As a result, a total of 56 trees were planted. How many teachers and students participated in this tree planting activity?
3月12日植树节这天，胜利小学师生参加植树活动，每4人分成一个小组，每组植树8棵，结果一共植树56棵．参加这次植树活动的师生一共多少人？
<gadget id="calculator">56 / 8</gadget>
<output>7</output>

<gadget id="calculator">7 * 4</gadget>
<output>28</output>

<result>28</result>