IP Calculation problem

I have a school assignment about IP that I wanna get help.

Case Description
A company plans to set up a number of local area networks (LANs) for its divisions as follows:

■sales division [LAN-SA: 25 computers; 1 file server; 1 network printer]
■marketing division [LAN-MA: 18 computers; 1 file server; 1 network printer]
■purchase division [LAN-PU: 12 computers; 1 file server; 1 network printer]
■accounting division [LAN-AC: 4 computers; 1 network printer]
■human resource division [LAN-HR: 5 computers; 1 network printer]

All computers will be able to access the Internet. The existing network equipment that the company has is listed below:

■one router (to connect to the Internet)
■two 4-port routers
■two 4-port switches
■two 24-port switches
■one 48-port switch

The private CIDR IP (v4) address ranged from 192.168.1.0 – 192.168.1.255 is used for all the computers and network devices for the company. Each device obtains its IP from a DHCP server when it is switched on.

(a) Suppose a fixed-length subnet mask is used, what should it be? Show all the relevant calculation. Give the range of IPs for each LAN.

(b) Suppose a fixed variable-length subnet masking (VLSM) technique is used, show all the relevant calculation. Give the range of IPs for each LAN.

thankssssss