$\frac{ -8a{b}^{7}{c}^{9} }{ 16{b}^{12}{c}^{4} }$
Simplify the expression$\frac{ -8a{b}^{7}{c}^{5} }{ 16{b}^{12} }$
Cancel out the common factor $8$$\frac{ -a{b}^{7}{c}^{5} }{ 2{b}^{12} }$
Simplify the expression$\frac{ -a{c}^{5} }{ 2{b}^{5} }$
Use $\frac{ -a }{ b }=\frac{ a }{ -b }=-\frac{ a }{ b }$ to rewrite the fraction$-\frac{ a{c}^{5} }{ 2{b}^{5} }$