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MathNet 2025 — 50 problems with figures (EN–VI) Question 2

Math Olympiad Vault · MathNet 2025 — 50 problems with figures (EN–VI)

Question 2

Let $k$ be a real number such that the system
$$
\begin{aligned}
|25 + 20i - z| &= 5 \\
|z - 4 - k| &= |z - 3i - k|
\end{aligned}
$$
has exactly one complex solution $z$. The sum of all possible values of $k$ can be written as $\frac{m}{n}$, where $m$ and $n$ are relatively prime positive integers. Find $m+n$. Here $i = \sqrt{-1}$.