7/ \(\frac{1}{xy-3x} \div \frac{1}{y-xy}\) 8/ \(\frac{x+1}{x+4} \div \frac{x^2-4}{x^2-16}\) 9/ \(\frac{x+1}{2x+6} \div \frac{2x+3}{y(x+3)}\) 10/ \(\frac{1-3x}{2x}, \frac{3x-2}{2x-1}, \frac{3x-2}{2x-4x^2}\)

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7/ \(\frac{1}{xy-3x} \div \frac{1}{y-xy}\)

8/ \(\frac{x+1}{x+4} \div \frac{x^2-4}{x^2-16}\)

9/ \(\frac{x+1}{2x+6} \div \frac{2x+3}{y(x+3)}\)

10/ \(\frac{1-3x}{2x} , \frac{3x-2}{2x-1} , \frac{3x-2}{2x-4x^2}\)