You can put this solution on YOUR website! -7x - y = -30
4x + y = 21
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-3x = -9 {added the two equations together, eliminating the y}
x = 3 {divided both sides by -3}
4x + y = 21 {original bottom equation}
4(3) + y = 21 {substituted 3, in for x, into 4x + y = 21}
12 + y = 21 {multiplied 4 by 3}
y = 9 {subtracted 12 from both sides}
