Finding the y value is easy if you know the slope of the line and the x coordinate. Review the equation for the slope of a line. The equation for finding the slope is: m = [y1 - y2] / [x1 - x2]. If you know x, you can solve for y to find the y value for the slope of the line.
The top angle is 50 because 180 - 130 = 50 Since the top angle is 50, the two bottom angles have to add up to 130. Since the bottom angles are the same, you can do 130 / 2 to find the angles which equals 65.
