can someone explain these two answer?

Consider the GO back N protocol with a sender window size of 3 and a sequence number starting from 1. At some time t, the receiver sends an acknowledgment for 6 (received all packets up to 6). What are the possible sequence numbers of packets in the sender's window at time t? If the sender has received all the previous acks then the window will be [6,7,8; if the sender has not received any of the acks in the window, then it will be [4,5,6] and [5,6,7] A TCP connection with a flow control window of 40 packets uses slow start with a minimum congestion window of 2 with ss thresh-40. How many RTTs are required to send 25 packets (with sequence number 1 through 25), assuming packet with sequence number 6 is lost and retransmitted. No other packets are lost. CW-2: 1,2 CW-4: 3,4,5,6 CW-7: 7,8,9,10,11,12,13 Retransmit 6 CW-2: 14,15 CW-4: 16,17,18,19 CW-8: 20,21,22,23,24,25 Answer: 7 RTTS Consider the GO back N protocol with a sender window size of 3 and a sequence number starting from 1. At some time t, the receiver sends an acknowledgment for 6 (received all packets up to 6). What are the possible sequence numbers of packets in the sender's window at time t? If the sender has received all the previous acks then the window will be [6,7,8; if the sender has not received any of the acks in the window, then it will be [4,5,6] and [5,6,7] A TCP connection with a flow control window of 40 packets uses slow start with a minimum congestion window of 2 with ss thresh-40. How many RTTs are required to send 25 packets (with sequence number 1 through 25), assuming packet with sequence number 6 is lost and retransmitted. No other packets are lost. CW-2: 1,2 CW-4: 3,4,5,6 CW-7: 7,8,9,10,11,12,13 Retransmit 6 CW-2: 14,15 CW-4: 16,17,18,19 CW-8: 20,21,22,23,24,25 Answer: 7 RTTS