1.
[tex](2x - 3y) + (2y - 3x) - (x - y) = 2x - 3y + 2y - 3x - x + y = - 2x[/tex]
2.
[tex](4x - 2xy - 1) - ( - 5x + xy + 1) = 4x - 2xy - 1 + 5x - xy - 1 = 9x - 3xy - 2[/tex]
3.
[tex](2x + y) + (x - 2y) = 2x + y + x - 2y = 3x - y[/tex]
