Answer:
 [-2,6] - {3} - {6}  =    [-2,3)  ∪   (3,6)
Step-by-step explanation:
Union Of Intervals
Let us assume two interval A =  (a,b) and  C = (c,d).
Their union is written as :   A ∪ C = (a,b) ∪ (c,d)
Now, if interval is written in form [a,b] ⇒  a and b are INCLUDED in interval
Also, if interval is written in form (a,b) ⇒  a and b are NOT INCLUDED in interval
Here, the given interval is [-2,6]
excluding 3 and 6 from this will give:
 [-2,3)  ∪   (3,6)
The first set is [-2.3)   where  -2 is INCLUDED but 3 is NOT INCLUDED.
The second set is (3,6)   where 3 and 6 both are  NOT INCLUDED.
Hence,   [-2,6] - {3} - {6}  =    [-2,3)  ∪   (3,6)