\text{1. Start with the fraction } \frac{a}{b} \text{ and set up the given condition:} \\\frac{a - nb}{b - na} = 2
\text{2. Cross-multiply to clear the fraction: } \\a - nb = 2(b - na)
\text{3. Distribute and simplify both sides:} \\a - nb = 2b - 2na
\text{4. Rearrange to collect all terms involving } a \text{ on one side and terms involving } b \text{ on the other:} \\a + 2na = 2b + nb
\text{5. Factor out common factors from both sides: } \\a(1 + 2n) = b(2 + n)
\text{6. Isolate } \frac{a}{b} \text{:} \\\frac{a}{b} = \frac{2 + n}{1 + 2n}
\text{7. Therefore, the fraction } \frac{a}{b} \text{ in terms of } n \text{ is } \frac{2 + n}{1 + 2n}