$A=\left \{ 1,2,3,4,5\right \}$
$B=\left \{0,3,6\right \}$
Now
1) $A\cup B=$ this set contains all the elements from either in $A$ or in $B$ or in both. so $A\cup B=\left\{0,1,2,3,4,5,6\right\}$
2) $A\cap B=$ This sets contains all the elements that are common in both the sets. That is: $A\cap B=\left\{ 3\right\}$
3) $A-B=$ all elements that are present in $A$ but not in $B$. That is : $A-B=\left\{1,2,4,5\right\}$
4 ) $B-A=$ all the elements that are presents in $B$ but not in $A$. that is: $B-A=\left\{0,6\right\}$