Ответ:

  1. \[\frac{3x-6y}{9x}=\frac{3(x-2y)}{9x}=\frac{x-2y}{3x}.\]
  2. \[\frac{2x(y+3)}{4y+12}=\frac{2x(y+3)}{4(y+3)}=\frac{x}{2}.\]
  3. \[\frac{2x^2+6xy}{x+3y}=\frac{2x(x+3y)}{x+3y}=2x.\]

Ответ: б) \(\frac{x-2y}{3x}\); г) \(\frac{x}{2}\); е) \(2x\).