$3\:x\left(7\:x\:2\right)$

$\left(6ab+10\right)\:\:\left(7a-26\right)$

$f\left(x\right)=-x-4$

$\left(-57\right)+\left(29\right)+\left(-16\right)+\left(84\right)+\left(109\right)$

$20-10x\le100$

$\log\left(x^2+5x\right)=2+\log\left(x+5\right)-\log\left(x-21\right)$

$\left(a-x\right)\left(x-a\right)$