need helpppppp plz .

Answer:
A) x=10
Step-by-step explanation:
All the angles in a triangle will add to equal 180°.
Knowing this, we can set up an equation.
(8x+5) + (5x-1) + (4x+6)= 180°
In order to solve, we must first combine like terms. (These can be found on the left side of the equation).
8x+5x+4x= 17x
5+ (-1) + 6= 10
We can now rewrite our equation as follows:
17x+10=180°
Subtract 10 from both sides.
17x+10=180°
- 10 -10
17x=170°
Divide by 17 on both sides.
17x=170°
---- -----
17 17
x= 10°
The answer is x=10°.