Liza is wrong because...
Friday = 237
Saturday = 237 + 446
Both days = 920
Answer:
B
Step-by-step explanation:
Two events A and B are called independent, when

where
is the probability that B occurs given that A has already occurred.
A = randomly selected person is a student
B = randomly selected person prefer "Vikings"
B|A = randomly selected student prefer "Vikings"
Probabilities:

Since

we can state that events are not independent.
I think the answer is: 6 = -21