$\frac{2x-9}{10}$

$8n-7y-12n+5-3y$

$\left(x+2\right)\left(2x^3-2x^2+3x-1\right)+-4$

$\lim_{x\to0}\left(\ln\left(\cos\left(5x\right)\right)\right)$

$3\cos^2\left(x\right)-\cos\left(x\right)=0$

$\left(+1\right)-\left(+3\right)-\left(-4\right)-\left(-5\right)$

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