a) $$y + \frac{3y}{y - 3}$$;

a) $$y + \frac{3y}{y - 3} = \frac{y(y - 3) + 3y}{y - 3} = \frac{y^2 - 3y + 3y}{y - 3} = \frac{y^2}{y - 3}$$.

Ответ: $$\frac{y^2}{y - 3}$$