find the value of x and y

Answer:
x=30
y=17
Step-by-step explanation:
We know that 6x+9 = 129 since they are vertical angles
6x+9 = 129
Subtract 9 from each side
6x+9 -9 =129-9
6x = 120
Divide by 6
6x/6 =120/6
x = 20
3y+129 =180 since they make a straight line and straight line are equal to 180 degrees
3y+129 =180
Subtract 129 from each side
3y+129-129=180-129
3y = 51
Divide by 3
3y/3 = 51/3
y = 17
[tex](6x+9)^o\ and\ 129^o\ are\ the\ vertical\ angles.\\\\\text{The vertical angles have the same measure. Therefore we have the equation:}\\\\6x+9=129\qquad\text{subtract 9 from both sides}\\\\6x=120\qquad\text{divide both sides by 6}\\\\\boxed{x=20}[/tex]
[tex]3y^o\ and\ 129^o\ are\ the\ supplementary\ angles.\text{}\\\\\text{Supplementary angles are two angles with a sum of }\ 180^o.\\\text{Therefore we have the equation.}\\\\3y+129=180\qquad\text{subtract 129 from both sides}\\\\3y=51\qquad\text{divide both sides by 3}\\\\\boxed{y=17}\\\\Answer:\ \boxed{x=20^o\ and\ y=17^o}[/tex]