Odpowiedź:
a) (c-1)*(2c+3d) = 2c^2 + 3cd - 2c - 3d
b) (x-1)*(2x+4) = 2x^2 + 4x - 2x - 4 = 2x^2 + 2x - 4
c) (x+7)*(3x-1) = 3x^2 - x + 21x - 7 = 3x^2 + 20x - 7
d) (-2x-7)*(5y-4) = -10xy + 8x - 25y + 28
e) (3x+6y)/3 - (2x-4y)/2 = x + 2y - (x - 2y) = x + 2y - x + 2y = 4y
