Question

Prove that;n(AUBUC)=n(A)+n(B)+n(C)-n(AnB)-n(BnC)-nCnA)+n(AnBnC)

Answer 1

The correct way of writing down the given formula is this as the given solution gives us nothing to prove:

n(AUBUC) = n(A)+n(B)+n(C) -n(AnB) -n(BnC) - n(CnA) + n(AnBnC)  

Answer 2

Using associative property on union of three sets i.e.,A,B and C it can be easily proved.