\[\boxed{\text{557\ (557).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[\textbf{а)} - 8a^{5}c^{3} = - 4a^{2}c^{3} \cdot 2a^{3}\]
\[\textbf{б)} - b^{6}y^{9} = b^{4}y^{3} \cdot \left( - b^{2}y^{6} \right)\]
\[\textbf{в)}\ 60x^{10}y^{15} = 5x^{7}y^{4} \cdot 12x^{3}y^{11}\]