please explain

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 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