The answer would be 13.9 kg of gravel used per square meter
        
                    
             
        
        
        
Answer:
it has one solution
Step-by-step explanation:
1.y=x-3 
2. 3y-3x sub x-3 in place of y therefore
it can also be written as 3x-3x-9=9
if you add 9 to both sides 3x-3x-9+9=-9+9
0+0=0
 
        
             
        
        
        
His commission is simply: $15,000 x 0.04 = $600