Y = 90 degrees
1) The angles on a straight line add to 180 degrees so 180-110= 70 degrees.
2) The angles in a triangle add to 180 degrees so 70+70= 140 degrees. The angle at the top of the triangle will have to be 40 degrees as 140+40= 180 degrees.
3) As x is half the angle at the top of the triangle (40 degrees), x will equal 20 degrees.
4) As the angles in a triangle add to 180 degrees 20+70=90 degrees 180-90=90 degrees.
5) Answer = 90 degrees