Question

If n(u)=60 n(a)=21 and n(b)=43 then the least value of aUb

Answer 1

n(u)=60
n(a)=21
n(b)=43
n(aub)=n(a)+n(b)-n(aUb)
60=21+43-n(aUb)
6o=64-n(aUb)
n(aUb)=64-60=4
I think you put the symbol 'U' as intersection then it means this is the answer.
Hope you got it.