Answer:
x = 53°
Step-by-step explanation:
Before the river gets divided into two different degrees its a straight angle.
If you add x° to (2x + 21)° it should equal 180°
Now you set it up to solve for x
x° + (2x + 21)° = 180°
Add the x's together
3x° + 21° = 180°
Then subtract 21° from 180°
3x° = 159°
Then divide both sides by 3 to get x
[tex]\frac{3x}{3} = \frac{159}{3}[/tex]
x = 53°
