First, find the value of x. Note that the angles x, 0.5x and 3x sum up to 4.5x, and that this sum has the value 180 degrees. Solving this equation for x, we get x = 40 degrees.
Now, 0.5x and 0.5y are vertical angles, and thus x = y. So, with x being 40 degrees, y = 40 degrees.
