{ x + 3 y = 7 * ( - 2)
2 x + 4 y = 8
{ - 2 x - 6 y = - 14
2 x + 4 y = 8
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-2 y = - 6 * ( -1)
2 y = 6
y = 6 / 2
y = 3
For x :
2 x + 4 y = 8
2 x + 4 * ( 3) = 8
2 x + 12 = 8
2 x = 8 - 12
2 x = - 4
x = - 4 / 2
x = - 2
Solution: x = -2 and y = 3
hope this helps!