Can someone please explain where I have gone wrong. I think the range is 32, but I can only see 30.This is because the range is the numbers between the subnet ID and the broadcast ID. This is 33-62. Noting that we cannot use 32 or 63 as ranges.

The range is therefore 32-62 or 30.

2.2. Suppose an organization owns the block of addresses of the form 129.17.129.97/27. Suppose it wants to create four IP subnets from this block, with each block having the same number of IP addresses. What are the prefixes (of form xxx.xxx.xxx/y) for the four IP subnets?

129.17.129.97 is a Class B network.

The subnet mask is 27 bits long.

This means that the subnet is 255.255.255.224 in decimal, or 1111 1111.1111 1111.1111 1111.111 0000 in binary.

The available range of IP addresses is 30. This means that the available IP addresses are available from 129.17.129.97-127.

The range of the four IP subnets is 30 / 4 = 7.5.

This does not make much sense. If the range was 32 it would make more sense.