Answer:
Approximately 18.0.
Step-by-step explanation:
To find <em>x</em>, we can use the Law of Cosines.
The Law of Cosines is the following:

Now that the <em>c</em> is the side we're trying to find. Thus, the <em>c</em> is <em>x</em>. Also, Angle C is the angle opposite to <em>c</em> (or <em>x</em>). <em>a </em>and <em>b</em> are the two sides next to Angle C.
Plug in <em>x </em>for <em>c</em>, 16 for <em>a</em>, 30 for <em>b</em>, and 30 for Angle C:

(Use a calculator. Make sure you're in degree mode!)