1) (3а)(-4b^2)=-12ab^2
2) (-1/2 m^3)(16m^2)=-8m^5
3) (4x^2 y^5z)(5x^3y z^2)=20x^5 y^6 z^3
4) (3/4x^2 y^3 z)*(2/3x^3 y^2 z^2)=1/2x^5 y^5 z^3
5) (-3/5a^2 x y^3)( 2/3a x^2 y)=-2/5a^3 x^3 y^4
6) (10 целых 1/3 a b^2 c^4)*( 1 целая 5/31 a^7 b c^2)=12a^8 b^3 c^6