Given:
A diagram of Aram's observations.
To find:
The measure of the missing angle.
Solution:
From the given figure it is clear that the three angles 
 lie on a single point and right side of a straight line.
 lie on a single point and right side of a straight line. 
So, the sum of angle 
 must be
 must be 
 .
.




Therefore, the measure of the missing angle is 
 .
.