Question

Let A, B, and C be subsets of a universal set U and suppose n(U)=100, n(A)=30, n(B)=30, n(C)=32, n(A∩B)=9, n(A∩C)=10, n(B∩C)=14, and n(A∩B∩C)=5.
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Compute n(Ac∩Bc∩Cc) c.

70
64
39
14
10
89

I dont understand this. Please help. Thank you.