Answer:
9
Step-by-step explanation:
The cardinality of a set - the number of terms in that set.
in the set {2, 4, 6, ... 18}
We can assume that the numbers follow a pattern: in this case, the pattern is multiples of 2 till 18 starting with 2.
so that means that the full set is
{2, 4, 6, 8, 10, 12, 14, 16, 18}
There are 9 numbers in that set;
so the cardinality of the set is 9
