My problem: There are $20$ students in a class. $13$ of them study chemistry and $16$ of them study physics. $3$ of them do neither.
$13 + 16 = 29$, but there are only $20$ people in the class, that means some people have to do both right? But how do I determine $C \cap P$? So, I said $20 -3 =17$, then $C \cup P$ must have a total of $17$ people. But then I am stuck.
Can someone please visually represent this? Mathematically showing how to find $C \cap P$ is also fine.