Wireshark · Wireshark-users: [Wireshark-users] how to understand the process of closing tcp connection

[wangyz <wangyz@xxxxxxxxxxxx>]

I want to understand the process of the closing tcp.
so i made this scen.
172.16.80.81 machine start telnet server.
172.16.80.80 telnet 172.16.80.81.
starup wiresharp on 172.16.80.80 and begin to catch the data.
exit telnet on 172.16.80.80.
then I got these data.
172.16.80.80 172.16.80.81 TCP compaq-https > telnet [ACK] Seq=7 Ack=16
Win=65279 Len=0
172.16.80.80 172.16.80.81 TCP compaq-https > telnet [FIN, ACK] Seq=7
Ack=16 Win=65279 Len=0
172.16.80.81 172.16.80.80 TCP telnet > compaq-https [ACK] Seq=16 Ack=8
Win=5840 Len=0
my question one :
how to understand [FIN, ACK].

my question two:
the process of closing tcp is four-way handshake.
why i only got three message.
thanks in advance