If a line is bisected by another, the 2 angles that make up the straight line will always add together for a total of 180 degrees. So the angle adjacent to the 137 degree angle will be
180 - 137 = 43 degrees.
All interior angles of a triangle add up to 180 degrees so now that we have another interior angles, we can find detailed the missing angle..
180 - 43 - 102 = 35 degrees
Now we find the adjacent able just like we did for the first angle..
180 - 35 = 145 degrees
