Please help WITH SETS

Question

Let A and B be subsets of a universal set U and suppose n(U)=190, n(A)=100, n(B)=70, and n(A∩B)= 50 Compute n(Ac).
?

a. 30
b. 10
c. 90
d. 40
e. 170
f. 20

Please help. Thank you

Answer 1

The answer ought to be C .

 

n(Ac) = 190 - n(A)

 

= 190 - 100

 

= 90