Answer: There are 4 people who only go to the game on Saturday.
Explanation:
Let the number of people go on Saturday be n(A).
Let the number of people go on Sunday be n(B).
Since we have given that
n(A) = 8
n(B) = 12
n(A∪B) = 16
According to rules, we get that

So, n(only go on Saturday) = n(only A) = n(A) - n(A∩B) = 8-4 = 4
Hence, there are 4 people who only go to the game on Saturday.