The shape in the middle is a quadrilateral, so the bottom right hand corner should add up to the rest of the angles to give 360 degrees.
40 + 80 + 110 = 230°
360 - 230 = 130°
The line on which x is on is a straight line, and a straight line is 180 degrees.
Therefore x has to be 180 - 130 to make sure it adds up to give 180 degrees.
180 - 130 = 50
∴ x = 50°
