Conjugating ratios without finding the numbers

Nonzero complex numbers \(z\) and \(w\) satisfy \(\dfrac zw=2-3i\). Use conjugate properties to find the following in Cartesian form without finding \(z\) or \(w\).

1. \(\dfrac{w^*}{z^*}\)[3]
2. \(\left(\dfrac{z+w}{z-w}\right)^*\). Explain why the denominator is nonzero.[4]