4) (5-2i)/(7+3i)

4) \(\frac{5-2i}{7+3i}\) = \(\frac{(5-2i)(7-3i)}{(7+3i)(7-3i)}\) = \(\frac{35 - 15i - 14i + 6i^2}{49 - 21i + 21i - 9i^2}\) = \(\frac{35 - 29i - 6}{49 + 9}\) = \(\frac{29 - 29i}{58}\) = \(\frac{1-i}{2}\) = \(\frac{1}{2} - \frac{1}{2}i\)