Finding the Least Common Multiple, 4, we can easily then divide each group (6th and 7 graders) by 4. 16 6th graders ÷ 4 = 4 groups 20 7th graders ÷ 4 = 5 groups So, the the 6th graders will have 4 groups each with 4 people (LCM). The 7th graders will have 5 groups each also with 4 people ( LCM). Hope this helps!