Given

Address: 205.16.37.39/28

• Prefix length $n = 28$, so host bits $= 32 - 28 = 4$
• Subnet mask: 255.255.255.240
• Block size $= 2^4 = 16$

Binary of the last octet

$39 = 0010\,0111$. The first 4 bits (0010) are network bits and the last 4 bits are host bits.

	Last octet (binary)	Address
Given	0010 0111	205.16.37.39
First address (host bits all 0)	0010 0000	205.16.37.32
Last address (host bits all 1)	0010 1111	205.16.37.47

Total number of addresses

$$2^{32-28} = 2^4 = \mathbf{16}$$

Answer

• First address: 205.16.37.32/28
• Last address: 205.16.37.47/28
• Total addresses: 16 (usable hosts: 14, from .33 to .46)