I'm sorry but it is against our
Rules to directly assist with classwork (assignments, homework, etc).
I can however tell you this. A
classless IP addressing scheme (aka. Classless Inter-Domain Routing, or
CIDR) is a scheme that does not restrict itself to the traditional class-based scheme (ie. Class A, Class B, Class C, etc.), and is used primarily to create subnets
within a pre-existing subnet. For starters, lay out the subnet you have given to you onto a piece of paper in binary (Base2), separating every eight bits (one byte, or
octet). This should leave you with a long string of converted binary with four chunks. Need to find out how many bits you have to play with? Well the address that was given to you has a mask of 21 bits (as shown with the /21). Starting from
the right, count left 21 bits and draw a big line down the page. Everything to the right of the line will be the bits you can play with (can be manipulated and broken down into subnets and hosts, etc). Everything to the left of the line is firmly a part of your network and can not be changed.
I'll leave the rest of the work to you. If you are unsure how to do the rest, I highly recommend you approach your tutor. I will however give you an important reminder/hint:
remember to subtract two (2) from your host count when forming a subnet. The first host address in the subnet is reserved for the network (the IP which represents the new subnet), while the last host address in the subnet is reserved for broadcast (the IP used to broadcast within that new subnet).