SOLUTION: n(B)=20, n(A^B)=5, n(AvB)=30 find n(A)

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Question 672623: n(B)=20, n(A^B)=5, n(AvB)=30 find n(A)
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
Just to be clear, in this context, A^B means "set A intersect set B"

n(A^B) = n(A) + n(B) - n(AvB)

5 = x + 20 - 30

5 = x - 10

5+10 = x

15 = x

x = 15

So n(A) = 15