Resposta:

[tex]\frac{9-2x}{x(x-3)}[/tex]

Explicação passo a passo:

[tex]\frac{1}{x-3} -\frac{3}{x} \\\\\frac{1}{x-3}(\frac{x}{x} ) -\frac{3}{x} (\frac{x-3}{x-3} ) \\\\\frac{x}{x(x-3)} -\frac{3(x-3)}{x(x-3)} \\\\\frac{x-3(x-3)}{x(x-3)} \\\\\frac{x-3x+9}{x(x-3)} \\\\\frac{9-2x}{x(x-3)}[/tex]