Answer:
Susan has 8 numbers belonging to just one list.
Step-by-step explanation:
Susan's 3 lists have 10 numbers each = 10 x 3 = 30 numbers
4 numbers appear on all three lists = 4 x 3 = 12 numbers
The remaining numbers after these 12 = 18 (30 -12)
Then, there are 5 numbers on 2 lists only = 5 x 2 = 10 numbers
The numbers on just one list = 18 - 10 = 8 numbers
Or
List 1 List 2 List 3 Total
Numbers on each list 10 10 10 30
Numbers on 3 lists -4 -4 -4 12
Numbers on 2 lists -5 -5 -0 10
Numbers on 1 list only 1 1 6 8
