solve by ADDITION METHOD x-3y=-5 -3x+9y=15 I got x=5 y=0?

x - 3y = -5

-3x + 9y = 15

Integer solution:

x = 3 n + 1, y = n + 2, n element Z

The equations are dependent. There are infinite solutions, described by either equation.

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Adding 3 times the first equation to the second gives 0 = 0, true for all x.

Doesn't look like it's correct.

Let's see what I get:

x - 3y = -5

-3x + 9y = 15

If by "addition method", they mean "elimination", we need to have the same variable have opposite coefficients. So if we multiply the first equation by 3, we get:

3x - 9y = -15

-3x + 9y = 15

Now we have a problem in that when we add these together, we get:

0 = 0

All variables have cancelled out. Since we are left with an always true statement, then there are an infinite number of solutions for this system (both lines work out to be the same line)