How can I recommend this to folks who want to learn SQL if the mathmatical operators aren't defined before questions are asked about them. It's pretty hard to google set union if you've never seen it before... I'd love some more explanation for the math.

The union of two sets is the set of elements which are in either set (8).

The intersection of two sets is the set of elements which are in both sets (5).

write exactly the correct integer. If the answer is 5 just type, 5 Click submit code don't hit run code. that's it

Just type the correct answer. Don't click "Run Code"

:-)

8

in this cases the refers to how many, totally of elements, one or two or three, etc..

when is union the symbol A U B intersect is A n B, (facepalm)

they have just asked to specify the number of elements in aUb.....which is 8......aUb means all elements in a and b without repetetion.

The solution cannot be submitted, I used a custom test case but it fails when I try submitting code. Did anyone encounter it?

I am not getting the editor for database . i am unable to answer. Please help me