All angles in a quadrilateral add to 360 x is supplementary to that other angle, call it y the angles inside are 40, 80, 110 and y 40+80+110+y=360 230+y=360 minus 230 both sides y=130 that is supplementary to x (adds to 180) x+y=180 x+130=180 minus 130 both sides x=50
Here, we know that sum of all the angles inside the figure will be 360. So, 40 + 110 + 80 + (180-x) = 360 [ ∠(180-x) is linear paired with x ] 230 + 180 - x = 360 410 - x = 360 x = 410 - 360 x = 50