First of all, recall the trigonometric identities
Where O = Opposite side, A = Adjecent side and H = Hypotenuse side
First Triangle:
As you can see, we know the angle and the adjacent side and the opposite side is unknown (x)
Therefore, the opposite side is 8.1
Second Triangle:
As you can see, we know the angle (37) and the adjacent side and the hypotenuse side is unknown (x)
Therefore, the hypotenuse side is 13.9
Third Triangle:
As you can see, the angle is unknown but the adjacent and opposite sides are given so we can use the tan identity.
Therefore, the missing angle is 17.1