Let $A$ and $B$ be sets with $|A|=10$ and $|B|=7$. What can we say about $|A \cup B|$?
In particular, find two numbers $x$ and $y$ for which we can be sure that $x \le |A \cup B|\le y$ and then find specific sets $A$ and $B$ so that $|A \cup B| = x$ and another pair of sets so that $|A \cup B| = y$.

Finally, answer the same question about the intersection between $A$ and $B$.

I know that $|A \cup B|=|A| + |B| - |A \cap B|$.
But I can't figure out what $x$ and $y$ values would work to make $x \le |A \cup B|\le y$ true.

I'm assuming |A U B| = 10+7-3, but also not sure if that's correct.