There is a straight line at the bottom which is 180 degrees. On the right side the angle measure is 150 degrees so you subtract that by 180 and you get 30 degrees making it supplementary. Next you should know that there is 180 degrees in a triangle. Now you formulate the equation 30+50+2x =180. Then you solve for x and you get the solution x=50 which is your answer. Now you can substitute 50 in for x and see if all the angle measures add up to 180 degrees.
If you can please make my answer the brainliest that would be much appreciated. Thanks!