$-20:4:\left(-5\right)+8.3$

$sin\left(9x\right)sin\left(4x\right)$

$-4\cdot12+-8$

$\frac{dy}{dx}\left(sin\left(xy\right)=y\right)$

$t=\left(x+2\right)^{2}-\left(x-2\right)^{2}+\left(x+4\right)^{2}-x^{2}-16$

$\left(-2\right)^4\cdot\left(-2\right)$

$-3-3.\left(1-10\right)$