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$\frac{x(x - 3)}{(x - 6)(x + 6)} \div \frac{x {}^{2} + 6(x - 6) - x(x - 6)}{x - 6} = \frac{x(x - 3)}{(x - 6)(x + 6)} \div \frac{x {}^{2} + 6x - 36 - x {}^{2} + 6x}{x - 6} = \frac{x(x - 3)}{(x - 6)(x + 6)} \div \frac{12x - 36}{x - 6} = \frac{x(x - 3)}{(x - 6)(x + 6)} \times \frac{x - 6}{12x - 36} = \frac{x(x - 3)}{x + 6} \times \frac{1}{12(x - 3)} = \frac{x}{x + 16} \times \frac{1}{12} = \frac{x}{12( x + 6)}$
ответ 1)