3x+9y=18 what is this answer?

Question

I just want to remember how I should convert them into proper equations so I can answer them correctly.

Answer 1

 

If it says "solve for x" or it just says "for x," then do this:

 

3x +9y =18

     -9y    -9y      (Isolate x by "moving everything else away from it" ==>"undo" by  using opposite operation)   
3x       = 18 - 9y

 

3x=18 - 9y 

3        3

 

x = 18 - 9y

        3    3 

 

x= 6 - 3y

 

 

 

3x + 9y =18

-3x          -3x

        9y = 18 -3x

 

9y = 18 -3x

9         9

 

y = 18 -3x

       9    9

 

y = 2 - 1x

            3

Answer 2

3x+9y=18    you could divide all terms by 3 to reduce the size of all numbers

 

x + 3y = 6   then subtract x from both sides

 

3y = -x + 6  then divide all terms on both sides by 3

 

y = (-1/3)x +2       answer is in slope intercept form for easy graphing

Answer 3

3x+9y=18

 

first eleminate 3x by taking away 3x from both sides.

 

3x+9y-3x=18-3x

 

9y=18-3x

 

then, divide both sides by the coefficient of y.

 

9y/9 = (18-3x)/9

 

y= 18/9 -3x/9

 

y= 2- x/9