Answer:
A. 30
Step-by-step explanation:
Because they equal each other, you can write the equation like this:
-7x+9 = -10x
Add 7x to both sides to get x on one side:
9 = -3x
To get x alone, divide both sides by -3:
x = -3
Then plug -3 into the x place on either angle R, or angle N. You get 30.
