Answer:
1
5
4
2
3
Explanation:
1 combines the sets A and B. that symbol there stands for U like "union". so, all values of x, where x is either < 1 or >= 5.
2 is again a union. A and C are combined. C contains only one element : x=5.
3 is again a union. B and C are combined. but the element of C (x=5) is already part of B (x>=5), so the union does not change anything, the result is simply B again.
4 is doing a "cross section" between the sets A and B. only elements that are in both sets are in the result. but x < 1 and x >= 5 don't have any elements in common. so, the result is an empty set.
5 is again a cross section. the only shared element between B and C is x=5.