please provide an explanation also

Part 2: (18 marks) A small business has five departments, Accounting, Sales, Purchasing, Production, and IT. The number of host addresses needed in each department is 6,50,15,30, and 4 , respectively. The subnet between the two routers needs two host addresses. The classful address assigned to the business is 192.168.54.0. The physical topology of the network is as shown below: Based on the above specifications, do a variable subnet design and fill the information in the tables below