Answer:
It is totaly based on the diagram
 
        
                    
             
        
        
        

 is already in simplest form because 23 is a prime number, which means that it is only divisible by 1 and itself (23). Hope this helps! :)
 
        
             
        
        
        
Answer:
A. x = 3
Step-by-step explanation:
5x+15 + 2x = 24 +4x
7x+15=24+4x
7x+15-15=24+4x-15
7x=4x+9
7x-4x=4x+9-4x
3x=9
3x/3=9/3
x=3
 
        
                    
             
        
        
        
The pair of equations: 
y = x + 4
 y = -2x - 2 
To solve the system of equation by substitution, you would substitute one variable for it's equivalent expression. Combining the pair of equations into one equation in only one variable. The easiest way to do this is by substituting out the variable y because it is already alone on one side of the equal sign. Substitute the y in the second equation for: x+4 
x+4 = -2x - 2 
solve for x 
x + 2x = -2 -4 
3x = -6 
x = -2 
now use the value for x to find y by putting into either equation. 
y = x + 4 
y = (-2) + 4 
y = 2 
solution is: (-2, 2)