Answer:
71°
Step-by-step explanation:
The sum of two interior angles in a triangle is equal to an exterior angle
m<x + m<y = m<z
4n - 18 + n + 9 = 151 - 5n
5n - 9 = 151 - 5n add like terms
10n = 160
n = 16
Since m<z = 151 - 5n we replace n with 16 and 151 - 5×16 = 71
