Explanation:
I didn't know this off of the top of my head, and I used Google to help me. Simply searching "30 60 90 right triangle" gave me a few very helpful links. For future reference, if no one is answering here, Google may be your friend.
The (credible) site that I found tells me
"The basic 30-60-90 triangle ratio is:
Side opposite the 30° angle: x
Side opposite the 60° angle: x * √3
Side opposite the 90° angle: 2x"
The side opposite the 30 degree angle is a value called "x" according to this site. This would mean that y is x, which is confusing, so we can just say that the value of y is y (if you want to go a little more in depth, I will simply be referring to what the site refers to as "x" as "y"). To begin, the side opposite the 30 degree angle, which is 8√3, is y * √3. This means that y is 8. Then, the remaining side is 2*y, which is 16.
Please let me know if you have any further questions or concerns.