The number of kids in your group is 12.
Explanation:
Let the number of kids=x
number of adults=y
total number of people=20
x+y=20(1)
cost of kids ticket=$4
cost of adults' ticket=$6
total cost=$96
4x+6y=96(2)
solving (1) and (2)
we get x=12
y=8
number of adults in the group y=8
number of kids in the group=12