theory : key point TCP is byte stream protocol means every byte sent is counted or numbered,
but in the question
all work is done on the network layer means in the network layer every packet sent is counted or numbered
now come to solution
packet sequence no is 8 bits
maximum life is 30 sec
so maximum no of packet we can send =28/30 packet per sec
given packet size is 600 byte
so maximum data can be send =600*28/30 byte per sec
so maximum data can be send =600*8*28/30 bits per sec
= 40960 bps