Are you serious!
{ } the empty set
All the sets containing one day {Monday} {Tuesday} {Wednesday} {Thursday} {Friday} {Saturday} {Sunday}
All sets containing two days eg {Monday, Tuesday} {Monday, Wednesday} etc
All sets containing three days eg {Monday, Thursday, Sunday} etc
All sets containing four days
All sets containing five days
All sets containing six days (missing a day)
The set contains seven days
There are 128 subsets and I got bored listing them all