If X and Y are two sets such that X has 40 elements, `X cup Y` has 60 elements and `X cap Y` has 10 elements, how many elements does Y have ?

Explanation

Here, `n(X) = 40`

`n(XuuY) = 60`

`n(XnnY) = 10`

We know,

`n(XuuY) = n(X) + n(Y) - n(XnnY)`

`=>60 = 40+n(Y) -10`

`=>n(Y) = 30`

So, Set Y has `30` elements.