Explanation:
your teacher gave you the law of sines already.
this was the only "trick" needed to solve this.
now, we just need to use it.
to be considered : a, b, c are always the sides opposite to the angles A, B, C.
so,
sin(28)/11 = sin(x)/22
sin(x) = 22×sin(28)/11 = 2×sin(28) = 0.938943126...
x = 69.87481894...° ≈ 69.9°