Help with moving x & y?

In general, you can either (i) move something to the other side and change its sign (+ve to -ve and vice versa), or (ii) do the same operation to both sides of the equals sign.

Method (i) is essentially one way of doing some of the (ii) procedures.

3x+y=-4 (example)

Subtract 3x from both sides:

y = -3x - 4

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You want Y by itself on one side ... so to do that with this problem ...

3x + y = 4

You must subtract 3x from both sides to get Y by itself so......

3x + y = 4

-3x - 3x

Now the Y is by itself and we have

Y = 4 - 3x

Do you see why it is like that now? Since we subtracted 3x from the right side we had to do it to the left side also, which actually moved it to the left side

Here is another example

10x - y = 7

So we do this

10x - y = 7

+10x +10x

Now we have -y = 7 + 10x

However, we want that -y to become a positive y. What do we do? We multiply both sides by negative 1 (because a negative X a negative gives us a positive.) so

(*-1) -y = 7 + 10x (*-1)

That gives us .... Y = -7x -10x

Just move the 3x. You have to subtract both sides by 3x so it will look like:

y = -3x - 4

y= -4-3x

This is because you have to subtract 3x from both sides like this:

3x-3x+y= -4-3x

This can be simplified into y= -4-3x

Hope this helps

simply subtract 3x

you minus the 3x and it cancels out.

then you minus 3x from -4

giving you y=-3x-4