Evaluate: $-4x$ if $x=3$

Evaluate: $x^{-1}$ if $x=5$

Evaluate: $\frac{x^4}{x^2}$ if $x=2$

Evaluate:$-\left(-x^2\right)$ if $x=3$

Evaluate: $-\left(-2xy\right)\$ if $x=5$ and $y=9$

Evaluate: $\left(5xy\right)^2$ if $x=4$ and $y=2$

Evaluate: $-2\left(-8\right)^{x+y}$ if $x=15$ and $y=-13$

Evaluate: $\left(-5x^0\right)$ if x=100

Evaluate: $6x^3$ if $x=2$

Evaluate: $\left(\frac{2x}{y}\right)^2$ if $x=3$ and $y=2$