Teacher Wang bought 640 pieces of candy and distributed them to 8 groups of students. There are 4 students in each group. How many pieces of candy are there on average?
王老师买了640块糖，把它们平均分给8个小组的同学，每个小组的同学有4人，平均每人多少块糖？
<gadget id="calculator">640 / 8 / 4</gadget>
<output>20</output>

<result>20</result>