3x + y = 5------> -6x - 2y = -10 {multiplied top equation by -2}
x + 2y = 0--------> x + 2y = 0 {bottom equation stays the same}
-5x = -10 {added the two new equations together}
x = 2 {divided both sides by -5}
x + 2y = 0 {bottom original equation}
2 + 2y = 0 {substituted -2, in for x, into bottom original equation}
2y = -2 {subtracted 2 from both sides}
y = -1 {divided both sides by 2}
