What is 4x^4 y^3 m^2 over 8x y r^0

4x^4 y^3 m^2 over 8x y r^0

do you mean   (4x^4 y^3 m^2) over (8x y r^0)

$\quad \frac{4x^4 y^3 m^2 }{ 8x y r^0}\\ =\frac{x^4 y^3 m^2 }{ 2x^1 y^1 *1}\\ =\frac{x^3 y^2 m^2 }{ 2}\\$