How to solve a system of equations? Help please

So we gotta solve ths system of equation for x and y and I try to solve for one variable and then use that to plug in to solve for the next but I can't get it right so confusing!

12x+3y=36
2x+4y=20

Soo..any one know the answer for x and y? Ok so all the options are positive numbers. 10 point for right answer

There are several ways to do this kind of problem.

One way would be to combine the equations in such a way that one of the variables cancels out, through multiplying one equation by a certain factor. One way to do this, for example, would be to take the second equation:

2x + 4y = 20

and combine it with the first equation

12x + 3y = 36

in order to have the x variables cancel out so we can solve for y, then plug in y to solve for x.

To do this, we can multiply the 2x in the second equation by -6 to get -12x, which would cancel out the x's when combined with the first equation's 12x. But, in order to keep the second equation true, we would need to multiply all parts of the equation by -6, to get:

(-6)*2x + (-6)*4y = (-6)*20
-12x - 24y = -120

which we can add to the first equation by combining like terms:

12x + 3y = 36
added to
-12x - 24y = -120
is
(12x - 12x) + (3y - 24y) = (36 - 120)
0x - 21y = -84
-21y = -84
21y = 84

Now you can solve for y easily by dividing both sides by 21, to get

y = 4

Plug in the y value into one of the equations (either one will work) and solve for x.

12x + 3y = 36
12x + 3(4) = 36
12x + 12 = 36
12x = 24
x = 2

OR

2x + 4y = 20
2x + 4(4) = 20
2x + 16 = 20
2x = 4
x = 2

So, your final answers are:

x = 2
y = 4

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A second way (and in my opinion a more difficult way) to do this would be to find what one of the variables equals in terms of the other. For example, using the second equation