$\frac{ -4 }{ 6-2\left( 4-5 \right) }$
Calculate the difference$\frac{ -4 }{ 6-2 \times \left( -1 \right) }$
Any expression multiplied by $-1$ equals its opposite$\frac{ -4 }{ 6+2 }$
Add the numbers$\frac{ -4 }{ 8 }$
Cancel out the common factor $4$$\frac{ -1 }{ 2 }$
Use $\frac{ -a }{ b }=\frac{ a }{ -b }=-\frac{ a }{ b }$ to rewrite the fraction$\begin{align*}&-\frac{ 1 }{ 2 } \\&\begin{array} { l }-0.5,& -{2}^{-1}\end{array}\end{align*}$