How do I decide which class of IP I choose for subnetting? [closed]

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5 departments are there-:

d1 d2 d3 d4 d5

d1 to d4 requires 20 hosts each and d5 requires 6 hosts.

these are various classes of ip addresses-:

A=>0-127=>network id=8, host id=24

B=>128-191=>nid=16,hid=16

C->192-223=>nid=24,hid=8

So how do I choose an IP address for my subnetting so that minimum loss of address space happens?

The answer is 202.53.69.0/24 with host bits of 5