1. The problem statement, all variables and given/known data Prove that A intersection B is a subset of A union B without using Venn diagrams 2. Relevant equations No relevant equations really 3. The attempt at a solution What i am thinking is this: A union B = A+B- A intersection B shows the intersection is within the union So A intersection B = -A union B +A+B, which tells me the intersection is smaller than the union. Can anybody give me some feedback please?