1) Suppose we have the following equation:
3x +y +6 = 2x -2y +4
To isolate both variables, we either add or subtract the other terms in this case, numbers we don't want on the left side.
3x +y +6 = 2x -2y +4 Subtract 6 from both sides
3x +y +6 -6 = 2x -2y +4-6
3x + y = 2x -2y -2
Now, in this case, we're going to subtract 2x and add 2y
3x +y -2x +2y= 2x -2y -2x +2y -2
3x +y -2x +2y = 0 -2
Now let's combine like terms.
x +3y=-2