First, you should see that the bottom right corner is an angle on the other side. So subtract 180 from 95 to get 85. Since all angles in a triangle add up to 180, You do 85 + 60 + x = 180. You simplify further to get 145 + x = 180.
Subtracting 145 from both sides leaves you with x = 35, which gives you C.
Next step is to complete the square on the left hand side of the equation and it would be balanced by adding the same number to the right side of the equation. It becomes
x^2 - 22x + (22/2)^2 = 10 + (22/2)^2
x^2 - 22x + (11)^2 = 10 + (11)^2
x^2 - 22x + (11)^2 = 10 + 121
x^2 - 22x + (11)^2 = 131
x^2 - 22x + 121^2 = 131
(x - 11)^2 = 131
Taking square root of both the left hand side and the right hand side of the equation, it becomes
x - 11 = ±√131
x - 11 = ±11.45
Adding 11 to the left hand side and the right hand side of the equation, it becomes