$-\frac{ 5 }{ 12 }\div\frac{ 3 }{ 6 }$
To divide by a fraction, multiply by the reciprocal of that fraction$-\frac{ 5 }{ 12 } \times \frac{ 6 }{ 3 }$
Cancel out the common factor $3$$-\frac{ 5 }{ 12 } \times 2$
Cancel out the greatest common factor $2$$\begin{align*}&-\frac{ 5 }{ 6 } \\&-0.8\overset{ \cdot }{ 3 } \end{align*}$