By the "vertical angles" theorem, when two lines cross, angles opposite one another have the same measure. So one of the angles inside the triangle is also x. Another angle in the triangle has measure 60 for the same reason and the third is "supplementary" to an angle with measure 140 so it has measure 180- 140= 40 degrees. Of course, the angle in the triangle must sum to 180 degrees. Can you find x now?