Thu gọn biểu thức:

a) \(\frac{3}{4}{x^3}{y^3}:\left( { - \frac{1}{2}{x^2}{y^2}} \right)\)

\[ = \left[ {\frac{3}{4}:\left( { - \frac{1}{2}} \right)} \right] \cdot \left( {{x^3}:{x^2}} \right) \cdot \left( {{y^3}:{y^2}} \right)\]

\[ =  - \frac{3}{2}xy.\]

b) \(\left( {30{x^4}{y^3} - 25{x^2}{y^3} - 3{x^4}{y^4}} \right):5{x^2}{y^3}\)

\( = 30{x^4}{y^3}:5{x^2}{y^3} - 25{x^2}{y^3}:5{x^2}{y^3} - 3{x^4}{y^4}:5{x^2}{y^3}\)

\( = 6{x^2} - 5 - \frac{3}{5}{x^2}y.\)

c) \({x^2}\left( {x - {y^2}} \right) - xy\left( {1 - xy} \right) - {x^3}\)

\( = {x^3} - {x^2}{y^2} - xy + {x^2}{y^2} - {x^3}\)

\( =  - xy.\)