Answer:
7
Step-by-step explanation:
The cardinality of a set is the number of elements in the set
Given the set W = x is a day of the week
The days of the week are {Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday}
Hence the set W will be;
W = {Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday}
n(W) = 7 (since there are 7 days in a week)
Hence the cardinality of the set W is 7