Question 26
A graph is symmetric about a line if the graph remains unchanged after reflection in that line. For how many quadruples of integers $(a, b, c, d)$, where $|a|, |b|, |c|, |d| \le 5$ and $c$ and $d$ are not both $0$, is the graph of
$$
y = \frac{ax + b}{cx + d}
$$
symmetric about the line $y = x$?
$$
y = \frac{ax + b}{cx + d}
$$
symmetric about the line $y = x$?