Exercise 1: The Full Mount-and-chroot Command Sequence — Possible Solution
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sudo mount /dev/sdXN /mnt
sudo mount /dev/sdXM /mnt/boot/efi
for dir in /dev /proc /sys; do sudo mount --bind $dir /mnt$dir; done
sudo chroot /mnt

Explanation:

This reproduces the chapter's own five-line sequence exactly, in the
correct order. The first line mounts the broken system's own root
partition (sdXN, standing in for whichever actual device/partition
number lsblk identified in Step 2) at the temporary mountpoint /mnt.
The second line additionally mounts the EFI System Partition (sdXM)
at /mnt/boot/efi -- included specifically for a UEFI system, per the
chapter's own note that this step only applies when there's a
separate ESP to mount. The for loop bind-mounts /dev, /proc, and /sys
from the live environment into the corresponding paths under /mnt --
per the chapter's own explanation, this is what gives the SOON-TO-BE
chrooted environment working device and process access, without which
most repair commands inside the chroot would fail. Only after all of
these mounts are in place does the final chroot /mnt command actually
enter the broken system's own environment -- doing this out of order
(chrooting before the bind mounts, for instance) would leave the
chrooted shell without working /dev, /proc, or /sys access.

WHY THIS WORKS AS AN ANSWER
------------------------------
This reproduces the chapter's own exact command sequence in the
correct order, explaining what each individual mount step
accomplishes and why the ordering (mounts before chroot) specifically
matters.