I really need help with this I don't understand it.

Answer:
(10x + 37) and (15x+7) are vertical angles which are always equal
10x + 37 = 15x +7
5x = 30
x = 6
The angle (15x +7) equals 97 and the other angle (10x + 37) also equals 97 degrees. All 4 of the angles add up to 360 degrees.
Therefore, 360 = 2z + 97 + 97
2z = 166
z = 83
Step-by-step explanation: