Protocols / Routing :: Partition Departmental IP Network Address Block To Create Staff / Student Subnet?

partition the departmental IP network address block to create a staff and a student subnet. Each of these will be identified by its own network address and netmask. It is university policy that you must be economical with the IP addresses. That is, the subnets must be as small as possible, but they must be large enough to accommodate the maximum number of hosts you were given. Also, it is university policy that the respective gateway router to the outside world should always be given the highest possible host IP address in the subnet. The student subnet should have a higher IP network address than the staff subnet. The network must be able to support up to 60 machines on the staff subnet (not counting the router) and up to 120 machines on the student subnet (also not counting the router).

IP address/netmask
University network address127.158.128.0
University network mask255.255.192.0
University internet gateway IP address127.158.191.254
Department network mask255.255.254.0
Department router address127.158.129.254

Suppose that the network address of the departmental network is 127.158.128.0 (calculated by AND between Dep network mask and Dep router address)I know that 60 machines would use 6 bits for the staff subnet.the netmask of staff would be 255.255.255.192.how can I figure out the the IP network address of the staff subnet.I have worked out the range for the staff subnetwork.

127.158.128.0 - 127.158.128.63
127.158.128.1 = Gateway address
127.158.128.63 = Broadcast address

Now how can I calculate the IP network address of the staff subnet?