assume a line is drawn down creating a triangle... and because we know that AB//CD... every line created makes a 90° angle as shown in my picture.
∡A) However that angle is 140°. So subtract 140°(Given ∡) -90° (perpendicular right ∡) --> ∡A=50°
∡B) so if this is true then 90°-35°=65° therefore ∡B= 65°
180°= ∡A+∡B+∡X
180°=50°+65°+∡x
180°=115°+∡x
∡x= 180°-115°= 65°