$20:\:10$

$\left(2m-3n\right)^5$

$x\frac{dy}{dx}+4y=5x-3x^2$

$\int\frac{x^2-5x+16}{\left(2x+1\right)\left(x^2-4x+4\right)}dx$

$\left(x+1\right)\left(x+2\right)+\left(x+2\right)\left(x+3\right)-2\left(x+5\right)\left(x+2\right)-2x$

$\frac{8a-z}{2n}-\frac{12x-m}{z}+\frac{2}{x}$

$\frac{\left(x^2-1\right)^2}{x^3}$