M∠P = 12°
m∠Q = 90° [A tangent line to a circle is perpendicular to the radius drawn to the tangent point]
m∠O = 90 - 12 = 78°
Answer: x=78°
The area of the square:

where "a" is a length of side.
Therefore:
X-y=34
x+y=338
We can use elimination in this problem.
2x=372
x=186
186+y=338
y=338-186
y=152