Answer:
80°
Step-by-step explanation:
The sum of the marked angles is 145°, so we have ...
(4x+5)° +(6x -10)° = 145°
10x -5 = 145 . . . . . . . . . . divide by °, simplify
10x = 150 . . . . . . . . add 5
x = 15 . . . . . . . . divide by 10
Then the measure of angle XMN is ..
angle XMN = (6x -10)° = (6(15) -10)° = 80°
______
Check
angle ZMX = (4(15)+5)° = 65°
and 65° +80° = 145° . . . . as required
