Final answer:
The rule for the nth term of the sequence is an = 6 + 6n, as the sequence is an arithmetic progression with a common difference of 6.
Step-by-step explanation:
To find the rule for the nth term of the sequence 12, 18, 24, 30, we need to determine how the sequence is progressing. The difference between consecutive terms is 6 (18-12, 24-18, 30-24), so it is an arithmetic sequence where each term is 6 more than the previous term. When n=1, the first term is 12, which can be expressed as 6+6. This suggests a rule of the form an = 6 + 6n when simplified to an = 6n + 6. Therefore, the nth term can be found by multiplying n by 6 and then adding 6.