From I: \( \dfrac{a}{b} = \dfrac{3}{5} \Rightarrow a = \dfrac{3}{5}b \)
From II: \( \dfrac{2a}{b} = \dfrac{12}{10} \Rightarrow \dfrac{a}{b} = \dfrac{6}{10} = \dfrac{3}{5} \)
Both statements essentially provide the same ratio \( \dfrac{a}{b} = \dfrac{3}{5} \), but no absolute values.
So, \( a \) can be \( 3, 6, 9, \ldots \), and so on — multiple values possible.