Substitution methode:
y=2x-5
4x-y=7
i thought you do it like this:
4x-2x-5=7
2x-5=7
2x=12
x=6
but that's not right.. what did i do wrong?

Quadrant 3

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Explanation:

pi radians = 180 degrees

If angle (greek letter theta) is in quadrant 1, then this places the angle in the northeast quadrant. Adding 180 degrees to theta will move it to the third quadrant, which is in the southwest.

Note: when incrementing through the quadrants (1,2,3,4) we move counterclockwise.