Here, we want to find the marked angles
As we can see, the angle marked e and 49 degrees are opposite each other
That makes them equal since they are vertically opposite angles
Thus, e = 49
Angle marked 49 and f lie on the same straight line
Mathematically, the sum of angles on a staright line is 180
Thus;
The angle beside the angle marked d is 90 degrees
Mathematically, the sum of angles on a straight line is 180
Thus;