$15\left(-23+\:6\right)\:$

$\frac{d^4}{dx^4}\left(3t^7-6t^4+8t^3-12t+18\right)$

$\lim_{x\to\infty}\:\left(\frac{ln\left(x+2\right)^5}{ln\:x^3}\right)$

$csc\left(100\right)-sec\frac{5\pi}{4}$

$\left(3b-n^2\right)\left(3b+n\right)$

$4\cdot3+2\cdot5-2$

$\sin t\:+\:\frac{\cos^2t}{\sin t}$