Subnetting Difficulty

Question

Since I don't have enough rep I posted the images here: Image1 Image2

Hello, taking the following example shown in the first image, Why my teacher has assigned in the solution(image 2) for network one (N1): 7+2 hosts? shouldn't it be 6+2 since the number of hosts in that network is 6 and the first and the last(broadcast) can't be assigned?

He has done the same things until N6 and N7 where he assigned 2+2 for the link.

Is this correct and there should be something that I need to know?

Thank you!

Answer 1

yes you are right because from 129:134 its available hosts and from 128:136 128 Network Address and 136 is a Broadcast Address so N1=6+2.