Erlang Calcultion in these case

I have a little bit confused about Erlang Calculation that they require step by step of calculation and they have
assumption follow :
1) GOS : P=0.01
2) Internal Call Duration = 120 Sec
3) External Call Duration = 180 Sec
4) Internal Call Distribution = 40%
5) External Outgoing Call Distribution = 30%
6) External Incoming Call Distribution = 30%
and they have maximum capapcity
– ISDN PRI Trunk = 2 Link
– Analog Trunk = 20
– Digital Extension = 100
– Analog Extension = 200
– Operator Console = 3
– IP License = 16
How many Erlang per trunk and per extension?
Please solve and send the solution to me with any document
or other assumption

Best Regads,
Boyu