You can find this by using Pythagorean Theorem to see how much cable is left for the other triangle.
so 50 - 20 = 30
So you know the hypotenuse and the opposite side for the other triangle.
A flagpole that stands on level ground. Two cables, r and s, are attached to the pole at a point 16 feet above the ground. The combined length of the two cables is 50 feet. If cable r is attached to the ground 12 feet from the base of the pole, what is the measure of the angle, x, to the nearest degree, that cable s makes with the ground?