$\cos\left(\frac{4}{5}\right)\cos\left(-\frac{12}{13}\right)-\sin\left(\frac{3}{5}\right)\sin\left(-\frac{5}{13}\right)$

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

$\frac{5}{sin\left(93-x\right)}=\frac{3}{sin\left(x\right)}$

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

$\frac{18x^2y-6xy^2+12xy}{-3xy}$

$\frac{4^9}{4^5}$

$4mn-8m^2n-2m$