please help me with this physics problem!!!!!?

Question

A record of travel along a straight path is as follows:
1. Start from rest with constant acceleration of 2.05 m/s2 for 20.0 s
2. Constant velocity for the next 2.70 min
3. Constant negative acceleration 8.77 m/s2 for 4.73 s
(a) What was the total displacement for the complete trip?
m
(b) What were the average speeds for legs 1, 2, and 3 of the trip as well as for the complete trip?
m/s
m/s
m/s
m/s

Answer 1

1) a = 2.05 m/s^2, t = 20.0s
v at the end is: at = 41.0m/s
distance traveled: at^2/2 = 410m
2) t = 2.70min = 162s
distance traveled: vt = 6642m
3) a = -8.77 m/s^2, t = 4.73 s
v at the end is: 41.0m/s + at = 41.0m/s - 41.5m/s = -0.5m/s
displacement: vt - at^2/2 = 193.9m - 98.1m = 95.8 m
(a) 410m + 6642m + 95.8 m = 7148m ≈ 7.15 km
(b) Leg1: 41.0/2 m/s = 20.5m/s
Leg2: 41.0/2 m/s
Leg3: {41.0/2 m/s - 0.5m/s}/2 = 20.3m/s
Complete trip: 7148m/ (20+162+4.73)s = 38.3m/s