Answer:2x-y-6=0 & 2x-y=6
Step-by-step explanation:
-3y=-6x+18. 
-3y+6x=18
-y+2x=6
2x-y=6
2x-1y=6
 2x-y=6 
 2x-y-6=0
 
        
                    
             
        
        
        
Let 

. Then 

. By convention, every non-zero integer 

 divides 0, so 

.
Suppose this relation holds for 

, i.e. 

. We then hope to show it must also hold for 

.
You have

We assumed that 

, and it's clear that 

 because 

 is a multiple of 3. This means the remainder upon divides 

 must be 0, and therefore the relation holds for 

. This proves the statement.