Consider the formulae,
[tex]\begin{gathered} \frac{ab}{cd}=\frac{a}{c}\times\frac{b}{d} \\ \frac{x^a}{x^b}=x^{a-b} \end{gathered}[/tex]
Now, solve the given expression as follows,
[tex]\begin{gathered} \frac{-12m^4}{-3m^3} \\ =\frac{-12}{-3}\times\frac{m^4}{m^3} \\ =4\times m^{4-3} \\ =4\times m^1 \\ =4m \end{gathered}[/tex]
Thus, the simplification yields '4m'.
