for the small triangle, <2=40, so we can add 40 to the 90 degree angles to get 130. subtract 180-130 to get the remaining angle in the small triangle to get 50.
The remaining angle, 50 is also the angle to the large triangle. So Since the top angle of the large triangle is =90. So add the 50 and 90 to get 140.Subt 180-140 because the total of the large angles should be 180 degrees. That leaves 40 degrees for angle z. So that would be B.