Answer:
z = 1
Explanation:
See the diagram of the triangle attached to this question.
We know the property of angles of a triangle as if we sum any two interior angles then we will get the opposite exterior angle.
Hence,
42z + 37 = 40z + (26z + 13)
⇒ 42z + 37 = 66z + 13
⇒ 37 - 13 = 66z - 42z
⇒ 24 = 24z
⇒ z = 1 (Answer)