How do I simplify this exponential expression?: $ 2(-3x^{-2}y^3)^{-1} \cdot (-3x^{-3}\cdot y)^2 $ How do I simplify this expression?
Simplify:
$$ 2(-3x^{-2}y^3)^{-1} \cdot (-3x^{-3}\cdot y)^2 $$
I tried and didn't get the answer. 

Hint: Note that $$ \left( ax^p \cdot bx^q \right)^e = \left( ab \cdot x^{p+q} \right)^e = \left( ab \right)^e \cdot x^{e\cdot(p+q)}. $$These are just usages of exponent properties. 
Solution, here: $$ \begin {align*} 2 \cdot \left( - 3 x^{-2} y^3 \right)^{-1} \cdot \left( -3 x^{-3} y \right)^2 &= 2 \cdot \left( - \dfrac {3y^3}{x^2} \right)^{-1} \cdot \left( - \dfrac {3y}{x^3} \right)^2 \\&= 2 \cdot \left( - \dfrac {x^2}{3y^3} \right) \cdot \left( \dfrac {9y^2}{x^6} \right) \\&= -6 \cdot x^{-4} \cdot y^{-1} = \boxed {-\dfrac {6}{x^4y}}. \end {align*} $$
