valid class C subnet addresses

I have a question about a)calculating the first 3 valid subnet addresses for the ip address with subnet mask 255.255.255.224
b)range of valid host addresses

For 255.255.255.224

First find the block size for the given subnet.
For class C address ssubtract the fourth octet from 256.

Block Size= 256-224 = 32

As we have the block size of 32, so each subnet for this subnet mask will be of
32 size.

Take the example of 192.168.120.0 IP add with sunet mask 255.255.255.224
The subnet for this will be-

192.168.120.0
192.168.120.32
192.168.120.64
192.168.120.96
192.168.120.128
192.168.120.160
192.168.120.192
192.168.120.224

**Note - The zero subnet i.e. 192.168.120.0 can be used if only you have "ip subnet zero" cmmnd enabled on
your devices"**

For finding the valid hosts in every subnet, write the subnets in following way-

192.168.120.0 192.168.120.32 192.168.120.64 ...
192.168.120.1 192.168.120.33 192.168.120.65
: : :
192.168.120.30 192.168.120.62 192.168.120.94
192.168.120.31 192.168.120.63 192.168.120.95

The first & the last entry in each subnet can not be assigned to any host.
As the first address in each subnet is the network address of that subnet &
the last address is the broadcast address for that subnet.
Rest address are the valid host addresses.
For Example-
192.168.120.32 subnet
192.168.120.32 - Network Add.
192.168.120.63 - Broadcast Add.

All other add. from 192.168.120.33 to 192.168.120.62 are valid host addresses!

i got another question, 14 valid subnets are to be created in a class B 130.23.0.0
determine the
1. required subnet mask
2.first 3 valid subnet addresses

(b)with reference to class A ip addressing scheme
1. sketch its structure ,showing network and host sections
2. state the range of valid network addresses
anyway thanks for the first question it helped a great deal

(a) for 14 valid subnets mask will be 255.255.240.0

block size will be of 16
subnets will be-

130.23.0.0 130.23.16.0 130.23.32.0 130.23.48.0 and so on.

(b) 1. For class A
nnnn.hhhh.hhhh.hhhh
n/w | h o s t

2. 1.0.0.1 to 126.255.255.254