. Let S3 be the set of integers in the interval [1, 25] that are divisible by 3.
Let S7 be the set of integers in the interval [1, 25] that are divisible by 7.
Describe the integers that belong to the set S3 U S7.
Determine the cardinality of S3 U S7, and the power | S3 U S7 |.