Odpowiedź :
ab - 2c + 2ab + 2c = 3ab
- 9xy 2 + 8x2y - xy2 - 7x2y + 4= - 10xy2 + x2y + 4
- 0,3m2n + 0,5m3 + 1,4m2n + 2m3 = 1,1 m2n + 2,5m3
ab - 2c + 2ab + 2c=3ab\\\\\\- 9xy^2 + 8x^2y - xy^2 - 7x^2y +4=x^2y-10xy^2+4\\\\\\ -0.3m^2n +\frac{1}{2} m^3 + 1,4m^2n + 2m^3=2\frac{1}{2}m^3+1,1m^2n