calculation of subnet mask, 1st available host address etc

I would like to know the method or the calculation involved or rather the basic fundamental behind calculating the following

1) If we are given a network ip say for example 130.71.0.0 and Maximum no. of Subnets=18 how can we calculate the
a)subnet mask
b)1st Available Host Address of Subnet 1
c)Maximum number of hosts/subnet

2)Now if we are given an ip address 80.57.95.222 / 26 (cidr)
how can we calculate the
a)subnet mask
b)network address
c)broadcast address

Make this a reference.. i found similar subject in the firewall.cx forum but i cant remember.. it helped me also


www.firewall.cx/ftopict-737.html

and this one also..

www.firewall.cx/ftopict-2145.html

hi there westewindshelly.. its worth reading the link provided by monsky..
i wont calculate and give u the compleate answers ill leave that to you.. as from the previous posts and forums i understand that we should not spoon feed...

u can make things more simple to calculate subnetmask by following the information provided below:->

subnetmask

---

max no of subnets
128

---

> 2
192

---

> 4
224

---

> 8
240

---

> 16
248

---

> 32
252

---

> 64
254

---

> 128

once u calculate subnetmask i think it should be simple for u to calculate the rest.. make shure that the first and the last network is not valid in case of cisco systems.. (still we can use the subnet zero command )....
i'd appereciate some one to make me correct if anything is wrong