Jeffrey wants to swim to his girlfriend who is straight across from him, on the other side of a river bank. The river has a current velocity of 4 km/h [W]. The width of the river is 300 m. If it takes Jeffrey 15 minutes to reach her, a) how fast should the boy swim to cross the river in exactly 15 minutes? b) what is his speed with respect to the river, as seen by the girl’s father who is in his own boat searching for his daughter’s whereabouts? c) What should Jeffery’s heading be in order for him to end up exactly where his girlfriend is?