We know:
The sum of the measures of the angles of a triangle is equal 180°.
Therefore we have the equation:
[tex](3x-16)+x+(x+6)=180\\\\3x-16+x+x+6=180\\\\(3x+x+x)+(-16+6)=180\\\\4x-10=180\ \ \ \ |+10\\\\4x=190\ \ \ \ |:4\\\\x=47.5[/tex]
m∠M = (3x-16)°
Substitute:
[tex]m\angle M=(3\cdot47.5-16)^o=(142.5-16)^o=126.5^o[/tex]
Answer: m∠M = 126.5°
