(a) Here, $V_{2} = V_{3}$
$ie.,\ i_{2} \times 1.5R = 3R \times i_{3}$
And $i_{2} + i_{3} = i$
$\Longrightarrow \ \ i_{2} = \frac{2i}{3}\ and\ i_{3} = \frac{i}{3}$
Now, $V_{i} = iR$
$\ \ \ \ \ \ \ \ \ V_{2} = \frac{2i}{3} \times 1.5R = iR$
$\ \ \ \ \ \ \ \ V_{3} = \frac{i}{3} \times 3R = iR$
$ie,\ \ \ \ \ V_{1} = V_{2} = V_{3}$