Two ships are moving along a line due east. The trailing ship has a speed relative to land based observation point of `64.0(km)/(h)`, and the leading ship has a speed of `45.0(km)/(h)` relative to that point. The two ships are in a region of the ocean where the current is moving uniformly due west at `10.0(km)/(h)`. The trailing ship transmits a sonar signal at a frequency of 1200.0 Hz. What frequency is monitored by the leading ship? Use `1520(m)/(s)` as the speed of sound in ocean water.