Find the number of addresses in a block of classless address

Find the number of addresses in a block of classless addresses if one of the addresses is 101.10.2.8/15.
Total addresses =
Usable addresses =

briefly explain the process

Solution

We have 15 bits for network address and 17 bits for host address.

Hence, total addresses will be 2^17=131,072.

Usable address will be 2^17-2=131,070

Subnet Mask will be: 255.254.0.0