\[8x^{3}y^{3} + 88x^{2}y^{3} - 16x^{3}y^{4} =\]
\[= 8x^{2}y^{3}\left( x^{3 - 2} + \frac{88}{8} - \frac{16}{8}x^{3 - 2}y^{4 - 3} \right) =\]
\[= 8x^{2}y^{3}(x + 11 - 2xy).\]