$\left(\frac{8}{6}z^6\right)$

$-4.5=-0.5\left(x-7.1\right)$

$\frac{2}{5}\left(12+y\right)=6-\frac{1}{4}\left(9-y\right)$

$6c-\left[-\left(2a+c\right)+\left\{-\left(a+c\right)-2a-\left(a+b\right)\right\}+2c\right]$

$7h-3h+2h^2-h+6h$

$\frac{12^5\cdot12^7}{-12^4}$

$y'-xy=x-1$