\[\boxed{\text{462\ (462).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[\frac{a}{b} = 3;\ \ \ \frac{b}{a} = \frac{1}{3}:\]
\[\frac{2a - 3b}{a} = \frac{2a}{a} - \frac{3b}{a} = 2 - 3 \cdot \frac{1}{3} =\]
\[= 2 - 1 = 1.\ \]