Question

if a and b are subset of union what is its meaning

Answer 1

The union is consist of a and b

Answer 2

given A and B are subsets of union that means SET A and SET B are subsets of union of A and  B
 for eg ,Let A be  (1,2,3)
                  B be   (5,6,7)
                    then AUB=(1,2,3,4,5,6) 
                    HERE BOTH A AND B ARE SUBSETS OF AUB