Whenever there is a square in a corner it always means it is a ninety degree angle. Im not sure that is what the question is asking but if it is the top with the square it a 90 degree angle.
Okay, the answer is 58°. In a quadrilateral, all the angles add up to 360°. Since you already know three of the angles (122°, 90°, 90°) you just subtract those three from 360° and you are left with 58°.
