- (2xy - 6x + 8) - (xy + 7x -5) =


2,5 x - ( 3,1y -2,5 x) - 1.9y =


(2a - 3b) - ( a + b) =



- (2c - 6d) - (-3c + 4d) =



(2x + 4y) + ( 3x + y) =