The mirror is 11 1/2 inches wide (that is, 11.5 inches) and the wall is 20 inches wide.
If we use the variable 'x' to represent the distance from the border of the mirror to the wall, we have the figure:
Then, we can write the following equation:
[tex]\begin{gathered} x+11.5+x=20 \\ 2x+11.5=20 \\ 2x=20-11.5 \\ 2x=8.5 \\ x=\frac{8.5}{2} \\ x=4.25\text{ inches} \end{gathered}[/tex]
So the distance from the mirror to each corner of the wall is 4.25 inches (or 4 1/4 in)
