Picture below. find y.

Hello!
We are given the opposite length, 9, along with the adjacent length y. The tangent is what deals with the opposite and adjacent sides. Let's find the tangent of 30.
tan30≈0.58
This gives us the equation below.
0.58=9/y
We multiply both sides by y.
0.58y=9
We divide both sides by 0.58.
y≈15.52
I hope this helps!