A river has a steady speed of 0.200 m/s. A student swims upstream a distance of 1.00 km and swims back to the starting point. If the student can swim at a speed of 1.10 m/s in still water,
a) how long does the trip take (swimming up and down in the current)?
b) If the water were still, by how much would the trip be longer or shorter? (Give a negative answer for a shorter trip.)