4. (10 Points) Recall the formula we discussed in class
P(A ∪ B) = P(A) + P(B) - P(A ∩ B)
Using this formula, prove that for any three events A, B, C we have the following identity
P(A ∪ B ∪ C) = P(A) + P(B) + P(C) - P(A ∩ B) - P(B ∩ C) - P(A ∩ C) + P(A ∩ B ∩ C)
You may also recall the distributive formula for probability of events/sets.