Step 1: Isolate Median from the correct empirical relation.
The correct relation is $\text{Mode} = 3\,\text{Median} - 2\,\text{Mean}$, which rearranges to $\text{Median} = \frac{\text{Mode} + 2\,\text{Mean}}{3}$.
Step 2: Substitute the given values to check the Assertion.
\[ \text{Median} = \frac{12k + 2(15k)}{3} = \frac{42k}{3} = 14k \]
This matches the Assertion, so the Assertion is true.
Step 3: Test the Reason's own formula with the same numbers.
The Reason claims $\text{Mean} = 3\,\text{Median} - 2\,\text{Mode}$. Plugging in gives $3(14k) - 2(12k) = 42k - 24k = 18k$, which does not equal the actual Mean of $15k$, so the Reason's formula is false.
\[ \boxed{\text{A is true, R is false}} \]