$$\left(yx^4z^3\cdot x^3y^3z^{-1}\right)^{-3}$$

$$17+\left(-36\right)-\left(-28\right)+15\left(-21\right)-\left(-24\right)-\left(-16-\left(-21\right)\right)$$

$$105\cdot6$$

$$\frac{x^4-x}{3x^2}$$

$$a2\:+\:5a\:+\:4\:$$

$$16m^2-40m+20$$

$$\lim_{x\to\infty}\left(\frac{2x^3}{e^x}\right)$$