Bài tập của em như thế này, nhờ mấy anh giúp đỡ

Cho địa chỉ IP sau:
150.128.7.100
255.255.192.0
Tính:
I. Major network
1) Network ID class
2) Major network address
3) Major broadcast address
4) Firt host and last host major network
II. Subnet
1)Number subnet bits
2)Number host bits
3)Subnet adress
4)Range of host address for subnet
5)Broadcast address for next subnet
6)Total number of useable subnet
7)Number valid host IP address for subnet
III. Given the major network – using VLSM
1)1 network 200 host
2)1 network 120 host
3)3 network 28 host
4) 3 wan link