The easiest way to solve this is to use a proportion
but first, make the 2 1/4 into a decimal. 1/4 equals .25
[tex] \frac{2.25}{x} = \frac{1}{48}
[/tex]
use butterfly method or cross mulitply to solve.
[tex]1*x=2.25*48
x=108
the barn door in real life is 108 inches