Answer:
The measure of ∠z   = 137°
Step-by-step explanation:
Here, angle 1  = 43°
To find : ∠z
Straight line Angle:  The angle which measures exactly 180° and is extended by a point on a straight line is called straight angle. 
 
According to the given figure:
   ∠1 + ∠z  = 180 °  (STRAIGHT LINE ANGLE)
or,   ∠z  = 180 ° - 43° = 137°
Hence, the measure of ∠z   = 137°.