$\left(5x^n-4\right)\left(5x^n+2\right)$

$\frac{dy}{dt}=-ty+4\frac{t}{y}$

$3\sin\left(x\right)+\frac{\sin\left(x\right)}{\cos\left(x\right)}$

$43.5\cdot9$

$\left(+16\right)x\left(-8\right)$

$\frac{1}{2}y-2=\frac{1}{3}y$

$10+21\left\{-3\left[\left(7-2\right)+7\left(3-2\right)\right]\right\}$