(x^2+27/6x^2-54 + 1/3-x) : x-3/6

$(\frac{x^2+27}{6x^2-54}+\frac{1}{3-x}):\frac{x-3}{6}= \\ \\=(\frac{x^2+27}{6(x^2-9)}+\frac{1}{-x+3}):\frac{x-3}{6}= \\ \\=(\frac{x^2+27}{6(x-3)(x+3)}-\frac{1}{1-3}):\frac{x-3}{6}= \\ \\=\frac{x^2+27-6(x+3)}{6(x+3)(x-3)}*\frac{6}{x-3}= \\ \\=\frac{x^2+27-6x-18}{6(x+3)(x-3)}*\frac{6}{x-3}= \\ \\=\frac{x^2-6x+9}{6(x+3)(x-3)}*\frac{6}{x-3}= \\ \\=\frac{(x-3)(x-3)}{6(x+3)(x-3)}*\frac{6}{x-3}= \\ \\=\frac{6(x-3)}{6(x-3)(x+3)}= \\ \\=\frac{1}{x+3}$

ну как то вот так....