please use my image as a reference (figure not drawn to scale).
AB is a straight line and the angle of a straight line = 180°
so that means [tex]5x + (6+x) = 180[/tex], solve for [tex]x[/tex]:
[tex]5x+(6+x)=180\\5x+6+x=180\\[/tex]combine like-terms
[tex]5x+x=180-6\\6x=174\\x=\frac{174}{6}[/tex]
[tex]x=29[/tex]°
if you want to make sure of the answer, plug in [tex]x[/tex] in the equation:
[tex]5x+(6+x)=180\\5(29)+(6+29)=180\\145+35=180\\180=180[/tex]
