In the sequence 12, 15, 18, 21, 24, 27, how many times does the number 21 occur?

A. 1

In the sequence 5, 10, 15, 20, 25, 30, how many times does the number 15 occur?

A. 1

In the sequence 2, 4, 6, 8, 10, 12, how many times does the number 8 occur?

A. 1

In the sequence 5, 10, 15, 20, 25, 30, how many times does the number 15 occur?

A. 1

In the sequence 7, 14, 21, 28, 35, 42, how many times does the number 28 occur?

A. 1