Slash Notation IP - What is what?

The /30 means all but two of the 32 bits are used to define the netmask. It also means you've got four IP addresses to play with. (But in reality, only two of which can be hosts)

Your last octet of the netmask is (in binary) 11111100, which leaves the last two bits for you to define your network. (hence the four addresses)

Just looking at the last two bits:

00 = 202.184.7.52 - I've forgotten why, but there's a reason you don't use 00.
                    My network theory is rusty.
01 = 202.184.7.53 - Host 1
10 = 202.184.7.54 - Host 2
11 = 202.184.7.55 - which is your broadcast address - sending to this should 
                    broadcast to all your hosts. Good for things like wakeOnLan 
                    packets.

Clear as mud I'm sure.. but hope that adds a little to your understanding

/20 means use the first 20 bits as a netmask. It's usually expressed where the bits outside the netmask are 0 so 206.89/16 is roughly 64K addresses all starting with 203.89. The netmask is 0xFFFF0000.

So 202.184.7.52/30 means:

    Network: 202.184.7.52
    Netmask: 0xFF FF FF FC

The last 2 bits are used for hosts within that subnet. See IP Routing on Subnets.

From 202.184.7.52/30 the ip is:202.184.7.52

Let us find the Netmask. /30 means 30 "1" s, 8 in the first octet, 8 in the 2nd, 8 in the 3rd and only 6 in the 4th.

We use the last octet only because we know eight '1's =255

128 64 32 16 8 4 2 1
 1   1  1  1 1 1 0 0 means we have six '1's
We add them to give 128=64=32=16=8=4=252

so Netmask becomes: 255.255.255.252

The number of hosts= 2^N -2 =2^2 -2 =2 ( since No of Zeroes in last octet is 2, so N=2)

Finding the network address:

202. 184. 7. 52 AND
255. 255.255.252

128 64 32 16 8 4 2 1
0   0  1  1  0 1 0 0 =52
1   1  1  1  1 1 0 0 =252 ANding

0   0  1  1  0 1 0 0

Replace the last two zeroes by 1

0   0  1  1  0 1 1 1 =55 to give the broadcast address
202.184.7.55