Answer:
[tex]x=21\textdegree[/tex]
Step-by-step explanation:
So we know that:
[tex]\angle A=3x-30 \text{ and}\\\angle B=2x-9[/tex]
And that the two angles are vertical angles.
Since they are vertical angles, their measurements are equivalent. Thus, to find x, set the equations equal to each other:
[tex]\angle A=\angle B\\(3x-30)=(2x-9)[/tex]
Now, solve for x. Add 30 to both sides. The left side cancels:
[tex](3x-30)+30=(2x-9)+30\\3x=2x+21[/tex]
Now, subtract 2x from both sides. The right cancels:
[tex](3x)-2x=(2x+21)-2x\\x=21[/tex]
Thus, the value of x is 21.
