MATH
posted by K. C .
Find A n B if A={5, 10, 15, 20} and B={10, 2O, 25, 30}
THAT N IS AN UPSIDEDOWN U, DON'T KNOW WHAT THAT MEANS

http://www.solvingmathproblems.com/mathsymbolssetintersection.html
It means intersection
which elements are in both sets? (overlap)
5 no
10 yes
15 no
20 yes
25 no
30 no
so
{ 10,20} 
The "upside down U" stands for intersection.
It means that you are looking for all elements which are common to both A and B
A ∩ B = {10,20)