There is no single "solution" to this equation. You can see that easily:
9 + 3 * 1 = 12
6 + 3 * 2 = 12
so this does not specify a unique x or y, but for any given x, there can be only one y.
In fact, it specifies an infinity of (x, y) pairs, that, if you graph them, will make a straight line.
Solve x+3y=12
1 answer