Answer:
The trees can be planted in 6 or 9 groups.
Explanation:
All the groups will have the same number of maple trees and dogwood trees.
The number of groups is a number that is both a factor of 36 and of 54.
Factors of 36: {1,2,3,4,6,9,12,18,36}
Factors of 54: {1,2,3,6,9,18,27,54}
The trees can be planted in 6 or 9 groups.