y=2x+4
10x-5y=-20
i know using the substitution method plays out like so...
10x-5(2x+4)=-20
10x-10x-20=-20
10x-10x=0
0=0
I have to express the answer in interval notation....how would I do that, and since the answer is 0=0 is their a value for x and y at all