$3\:-\:\left[\left(5\:-\:8\right)\:-\:\left(3\:-\:6\right)\right]\:$

$4x^2y^5z^3-2x^2y^{10}z^6$

$\lim_{x\to2}\left(\frac{x^2-x-2}{x^2-1}\right)$

$7\cdot\left(5+30s-45t\right)$

$x\frac{dy}{dx}+y=\frac{1}{1+x^2}$

$\:\left(3x\:+\:2y\:+\:5z\right)\:-\:\left(8x\:+\:2y\:+\:3z\right)\:$

$\left(2x+y+3z\right)+\left(x-y+z\right)$