15. Kayla wishes to swim from one side of a river, which has a current speed of 2 km/h, to a point on the other side directly opposite from her starting point. She can swim at a speed of 3 km/ h in still water. a. At what angle to the bank should Kayla swim if she wishes to swim directly across? b. If the river has a width of 300 111, how long will it take for her to cross the river? c. If Kayla's speed and the river's speed had been reversed, explain why it would not have been possible for her to swim across the river