Ответ:

  1. \(\displaystyle \frac{39x^3y}{26x^2y^2}=\frac{3x}{2y}\).
  2. \(\displaystyle \frac{5y}{y^2-2y}=\frac{5y}{y(y-2)}=\frac{5}{y-2}\).
  3. \(\displaystyle \frac{a^2-b^2}{3a-3b}=\frac{(a-b)(a+b)}{3(a-b)}=\frac{a+b}{3}\).

Ответ: а) \(\frac{3x}{2y}\); б) \(\frac{5}{y-2}\); в) \(\frac{a+b}{3}\).