$\frac{-9xy+3x^2}{3mx^2y^5}-\frac{4x^2-y}{2my}$

$\left(2+3\right).\left(5-7\right).\left(3+2-8\right)-4$

$\lim_{x\to0}\left(\frac{4x-3\tan\left(x\right)}{2\sin\left(x\right)-x}\right)$

$-\left(-1\right)-1$

$\left(2a^2-3b\right)^2$

$\left(-5x^5y^3\right)^3$

$\lim_{x\to1}\left(\frac{x-1}{x+1}\right)$