Answer:
D. 
Step-by-step explanation:
 
        
             
        
        
        
Answer:
x = 9
Step-by-step explanation:
Sum of a triangle is 180°.
6x + 1 + 6x - 14 + 9x + 4 = 180°
Arrange the like terms together and simply this equation.
6x + 6x + 9x + 1 + 4 - 14 = 180°
21x - 9 = 180°
Shifting '-9' to the other side of the equation gives you '+9'
21x = 180° + 9
21x = 189
Shifting 21 to the other side of the equation (to get x) makes it  ÷21 (multiply)
x = 189 ÷ 21 
x = 9
 
        
             
        
        
        
Answer: -4
Step-by-step: 
-x^2+5x-1 x _ = 4x^2-20x+4
4x^2-20x+4 / -x^2+5x-1
In the blank the answer would be -4 which is the monomial.