Answer
$x = 29.9^{\circ}$
Work Step by Step
You would use the Law of Sines here because you have the measure of two sides and a non-included angle, and you need to find the measure of the angle opposite to one of the sides.
Let's set up the formula for the Law of Sines to calculate $m \angle x$, the measure of the angle opposite to the side with a length of $11$ ft.:
$\frac{sin 115}{20} = \frac{sin x}{11}$
Multiply each side by $11$:
$11(\frac{sin 115}{20})$ = sin $x$
Take $sin^{-1}$ of both sides to solve for $x$:
$x = 29.9^{\circ}$
