Exercise 30.
Find all sets \(A\text{,}\) \(B\text{,}\) and \(C\) which satisfy the following.
\begin{align*}
A = \amp \{1, \card{B}, \card{C}\}\\
B = \amp \{2, \card{A}, \card{C}\}\\
C = \amp \{1, 2, \card{A}, \card{B}\}\text{.}
\end{align*}
Find all sets \(A\text{,}\) \(B\text{,}\) and \(C\) which satisfy the following.