Equations. Solve for y or just solve. 2x-4y=12 and -3y=3x-9.

I'm taking guess here that you will be using substitution.

Divide this whole equation (-3y=3x-9) by -3. Making y all by itself.

y=-x+3

Then plug in y=-x+3 in the other equation in the the other y.

So:

2x-4(-x+3)=12
2x+4x-3=12
6x-3=12
6x=15
X=5/2

Now plug in 5/2 into the x place of any of the equations to alone for y.

2(5/2)-4y=12
5-4y=12
-4y=7
Y=-7/4

So, I'm thinking those are the answers.

{5/2,-7/4}

2x - 4y = 12
divide thru by 2 to get

x - 2y = 6

and for -3y = 3x - 9
divide thru by 3 to get

-y = x - 3
add 3 to both sides to get
3 - y = x
plug x into first simplified equation to get

(3 - y) - 2y = 6
3 -y -2y = 6
3 - 3y = 6
-3y = 6 - 3
-3y = 3
y = -1
so,
x = 4, after plugging in -1 for y into either equation.

Rewrite...

2x - 4y = 12 1) ................. multiply 1) by 3

-3x -3y = -9 2)................. multiply 2) by -4 ( to get the y's the same so that they disappear)
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6x - 12y = 36

12x + 12y = 36 ... now add
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18x = 72

x = 72/18

x = 4

Now, substitute for x in -3y = 3x -9 .....

-3y = 3(4) - 9

-3y = 12 - 9

-3y = 3

y = 3/-3

y = -1

so x = 4, y = -1

from first equation y = (2x - 12)/4 = 0.5x - 3
substitute this into second equation -3(0.5x - 3) = 3x - 9
= -1.5x +9 = 3x - 9
so -3x-1.5x = -18
- 4.5x = -18
x = 4

2x-4y=12
-4y=12-2x
Y=-3+.5x

-3(-3+.5x)=3x-9
9+1.5x=3x-9
18=1.5x
18/1.5=x
X=12

Y=-3+.5(12)
6-3=3

X=12
Y=3
God that took forever

2x - 4y = 12 <=> 2x = 12 + 4y <=> x = 6 + 2y

-3y = 3*(6+2y) - 9 = 18 + 6y - 9 = 9 + 6y <=> -9y = 9 <=> y = -1

=> x = 6 + 2*(-1) = 6 - 2 = 4