write an equation
(8x)+90+(4x+6)=180
8x+90+4x+6=180
combine like terms
8x+90+4x+6=180
(8x+4x)+ (6+90)=180
12x+96=180
isolate the variable
12x+96=180
12x+96-96=180-96
12x=84
Solve for the variable
12x=84
12x/12 = 84/12
x=7
substitute for x
8*7=56
4*7+6= 34
add angle measurements to check work
56+34+90=180