Answer:
x = 30
Step-by-step explanation:
Vertical angles (angles that form when 2 lines forms a cross) are equal.
The vertical angle (top left of 3x + 10 angle) of the "3x + 10" angle is the angle ADJACENT to 80 degree angle.
When we have 2 adjacent angles like this, their sum is equal to 180, so that angle would be:
180 - 80 = 100
Now, this 100 degree angle is a vertical angle to "3x+10" angle. So they are EQUAL. We can write an equation and solve for x now:
[tex]3x+10=100\\3x=100-10\\3x=90\\x=\frac{90}{3}\\x=30[/tex]
Hence, x = 30
