The function describing the predicted velocity as a function of time, v(t), for a student-designed prototype two-stage model rocket during a 5.5 s time interval is given by v(t) = at + t + yt, where a = 3.0 m/s, B = 24 m/s, and y = 54 m/s. Due to ignition rates of the fuel in the two stages and external forces acting on the rocket, the design produces a velocity function that has both a local minimum and a local maximum during the time interval. Part F Determine the times at which v(t) has a local minimum and maximum. Express your answer as two numbers separated by a comma.