+--------------+
| Car Dealer |
+--------------+
/|\
/ | \
/ | \
+---+----+
| Buy Car |
+---+----+
|
+-----------------+
| Customer Data |
+-----------------+
|
+-----------------+
| Car Details |
+-----------------+
|
+----------------------+
| Calculate Price |
+----------------------+
V
+-----------------+
| Generate Invoice |
+-----------------+
/|\
/ | \
/ | \
/ | \
/ | \
/ | \
/ | \
/_______|_______\
