Hello, I hope you are doing well

This problem can be solved using the formula:

S = Ut + 1/2at ²

Case 1:

200 = 2u + 2a

u + a = 100.....(1)

Case 2: (for next 4 seconds)

distance = 420 cm, time = 6s

420 = 6u + 18a

u + 3a = 70.....(2)

On solving equation (1) and (2) we get,

u = 115 cm/s, a = -15c m/s ²

Now, using v = u + at

v = 115 - 15*7

v = 10 cm/s

Hope this helps