Problem of the Week
Problem D
Reflect on This

$\mathrm{△}ABC$ has vertices $A(2,1)$, $B(5,8)$, and $C(1,c)$, where $c>0$.

Vertices $A$ and $B$ are reflected in the $y$-axis, and vertex $C$ is reflected in the $x$-axis. The three image points are collinear. That is, a line passes through the three image points.

Determine the coordinates of $C$.