Question

if x and y are two sets such that n(x)=40 n (xuy)=60 n (xny)=10 find n (y) =?​

Answer 1

Answer:

n(x)=40

n(x u y) = 60

n(x n y) = 10

Now,

n(x u y) = n(x) + n(y) - n(x n y)

60 = 40 + n(y) - 10

60 = 30 + n(y)

n(y) = 60 - 30

= 30