2/5x - 1 = 9
 +1 +1
 10
—— ——
2/5 2/5
x = 50
        
             
        
        
        
Answer:
3
Step-by-step explanation:
1926/9=214
1923+3=1926
 
        
             
        
        
        
Answer:
Y=-3/2
Step-by-step explanation:
-2y+3=-4y
Move constant to the right  by adding its opposite to both sides
-2y+3-3=-4y-3
Eliminate the opposites 
-2y=-4y-3
collect the like terms
-2y+4y
collect the like terms
(-2+4)y
Calculate the sum
2y=-3
divide both sides of the equation by 2
2y÷2=-3÷2
Any expression divided by itself equal 1
y=-3÷2
y=-3/2
 
        
                    
             
        
        
        
Answer:
D. 14 Please mark as brainliest!
 
        
                    
             
        
        
        
Hi there!

We are given:
cos(7x)cos(4x) = -1 - sin(7x)sin(4x)
Begin by moving all terms with variables to one side:
cos(7x)cos(4x) + sin(7x)sin(4x) = -1
The corresponding trig identity is cos(A - B). Thus:
cos(7x - 4x) = cos(7x)cos(4x) + sin(7x)sin(4x) = -1
cos(3x) = -1
cos = -1 at  π, so:
3x = π
x = π/3
We can also find another solution. Let 3π = -1:
3x = 3π
x = π
Thus, solutions on [0, 2π) are π/3 and π.