Answer:
100 degrees
Step-by-step explanation:
You can get the measure of b by knowing that a straight line is 180 degrees. So the interior angle formed at R is 40 degrees. That makes the angle at p 40 degrees. The interior sum of a triangle is 180 degrees.
So 40+40+angle at a = 180
angle at a = 180-80 = 100 degrees.
