Calculate the velocity of the object in the graph during the following time interval 0-6 seconds. also, during which time interval is the object accelerating and how can you tell?

Cathy is pedaling down a steep hill on her bicycle and wants to be able to coast up the next hill, which is 25 meters high, without pedaling. cathy and her bicycle have a mass of 75 kg. assuming her bicycle is 100% efficient, what would her speed have to be?