$\:\left(ab\:-\:abc\:-\:abcd\right)\:+\:\left(-\:ab\:-\:abc\:-\:abcd\right)\:+\:\left(-\:ab\:+\:abc\:-\:abad\right)$

$4x^2-16x-3$

$\frac{\left(\left(2^3\right)^4\cdot2^2\right)}{2^5}$

$-\left(-10\right)-\left(-20\right)-\left(-15\right)$

$\infty^{-0.0000000000001}$

$4x+4+-9x+12y-10y$

$\frac{\cot\left(-t\right)+\tan\left(-t\right)}{\sin\left(t\right)}=-\sec\left(t\right)$