How do you simplify and write 1/(3x^-3y^-7) with positive exponents?

$\frac{1}{3 {x}^{-} 3 {y}^{-} 7} = \frac{1}{3} {x}^{3} {y}^{7}$
$\frac{1}{3 {x}^{-} 3 {y}^{-} 7} = {\left(3 {x}^{-} 3 {y}^{-} 7\right)}^{-} 1 = \frac{1}{3} {x}^{3} {y}^{7}$