Answer: n(A∪B∪C)= n(A) + n(B) + n(C)- n(A∩B) - n(B∩C) - n(A∩C) + n(A∩B∩C)
Step-by-step explanation: It is written wrong the correct formula is written above. It is a basic formula of set theory where the intersection of 3 elements gives the following. There are also formulas for 2 elements. This kind of formula is also present in probability theory. This is a vital formula that helps with many problems.