Compute all parts of given question:
Question: A dolphin wants to swim directly back to its home bay, which is 0.840 km due west. It can swim at a speed of 4.50 m/s relative to the water, but uniform water current flows with speed 2.79 m/s in the southeast direction.
Part A: What direction should the dolphin head?
Part B: How long does it take the dolphin to swim the 0.840-km distance home?
Explain the each and every step in detail for help.