Answer :
The arithmetic sequence is increasing in 12 each time
18, 30, 42, 54, 66
12n 12, 24, 36, 48, 60
To get from 12n to the arithmetic sequence, you add 6 each time
Therefore the answer is C - an = 12n + 6
18, 30, 42, 54, 66
12n 12, 24, 36, 48, 60
To get from 12n to the arithmetic sequence, you add 6 each time
Therefore the answer is C - an = 12n + 6