Solve: $5xy- 15 x^2 y +20 xy ^2$

Question

$\begin{array}{1 1} (1-3x+4y) \\ 5xy(1-3x+4y) \\ (x^4+y^4)(x^2-y^2) \\ (x^2+y^2)(x^2-y^2) \end{array} $