Try this:
Mult. the 2nd eqn by 3:
6x-3y=18
-2x-y=-6 => -6x - 3y = -18
To this result
add the 1st eqn: 6x -3y = 18
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Adding these
eqns together: 0 = -6y = 0. This can be solved for y: y = 0. Then
-2x - 0 = -6, and x = 3.
This system has the solution x=3, y=0: (3,0). Check it!
Thus, we dub this system of linear equations "consistent."