`a)-1/3 x^2y. 3/2xy^3=(-1)/3 . 3/2 .(x^2.x).(y.y^3)=-1/2 x^3y^4`
`b)-5xy^4.(-0,2x^2y^2)=[(-5).(-0,2)].(x.x^2).(y^4.y^2)=x^3.y^6`
`c)(-2x^2y).(5x^3y^3)=[(-2).5].(x^2.x^3).(y.y^3)=-10x^5.y^4`
`d)(-1 1/2x^2y^3)^2=[(-3)/2x^2y^3]^2=(-3/2)^2.(x^2)^2.(y^3)^2=9/4x^4y^6`