host addresses

Which VLSM mask will allow for the appropriate number of host addresses for Network A?

Which IP addressing scheme best defines the address range and subnet mask that meet the requirement and waste the fewest subnet and host addresses?

0/23 into a /27 mask, and how many usable host addresses will there be per subnet?

19/28, which of the following are valid host addresses on this subnet?

Which of the following host addresses are members of networks that can be routed across the public Internet?