the equation for acceleration is the ff:
2ad = V2^2 V1^2
V1 = 0
V2 = 120 km/h = 33.33 m/s
d = 240
inputting into the equation you get 2.31 m /s^2 as the acceleration
for B use another acceleration equation
a = change in V/ change in time
2.31 = (33.33 - 0) / (t2 - 0)
t2 = 14.43 seconds