(3x^2) * (4xy^3)=12x^3y^3=12*2^3*(-\frac{1}{2})^3=
=12*8*(-\frac{1}{8})=12*(-1)=-12
…
(10xy^4) * (\frac{1}{2} x^4y)=5x^5y^5=5*2^5*(-\frac{1}{2})^5=
=5*32*(-\frac{1}{32})=5*(-1)=-5
…
(-\frac{ 1}{2} x^3 y^2) * (3x^4y)=-1,5x^7y^3=
=-1,5*2^7*(-\frac{1}{2})^3=-1,5*128*(-\frac{1}{8})=
=-1,5*(-16)=24
…
(-x^2) * (xy^2) * (\frac{1}{2} x^ 3y^2)=0,5x^6y^4=
=0,5*2^6*(-\frac{1}{2})^4=0,5*64*(\frac{1}{16})=2