Step 1 :\[\frac{28 z^{6} y^{7}}{-4 z^{3} y^{4}} = -7 z^{3} y^{3}\]
Step 2 :\[\frac{-16 z^{4} y}{-4 z^{3} y^{4}} = 4 z y^{-3}\]
Step 3 :\[\frac{-7 z^{4} y^{5}}{-4 z^{3} y^{4}} = \frac{7}{4} z y\]
Step 4 :\[\boxed{-7 z^{3} y^{3} + 4 z y^{-3} + \frac{7}{4} z y}\]