If S and T are two sets such that S has 21 elements, T has 32 elements, and `Snn T`has 11 elements, how many elements does `Suu T`have?

Explanation

Here, `n(S)=21,n(T)=32,n(ScapT)=11`
Now, `n(S cup T)=n(S)+n(T)-n(S cap T)`
`rArrn(S cupT)=21+32-11=42`
Therefore, number of elements in `(S cup T)=42`.