First, using b= 70, fill in the vertical angle 70and the supplementary
angles 110. Now, if you know that a=40 and the bottom right angle
of the top triangle =110, then you know that the bottom left angle of that
triangle =30 (40+110+30=180). Now fill in the vertical angle across
from 30 as 30 the supplementary angles as 150. Look at the triangle
with angles a, c, and y. Since you know that a=40 and c=50, then
you know that y must be 90 (40+50+90=180). If y= 90, then fill in
the vertical angle across from y as 90. So in the furthest left triangle,
you have 30 and 90 filled in as angles, which makes angle x = 180 – 30
– 90 = 60. So 60 + 90 = 150.