Alright, so first we need to establish two things.
First, the compliment of a set is like the extreme opposite; everything that is not in set B will be in the complement.
Second, we need to find out what B is.
Okay, so B is everything that is greater than 2, that's given. That includes 3, 4, and 5. B = {3, 4, 5}. There are three items in this set.
The numbers that aren't included are 1 and 2. The complement of B, let's call this C I guess, is C = {1, 2}. There are 2 items in this set.
The answer, I believe, is two. Hope this helps!
