Final answer:
To find the rule for the nth term of an arithmetic sequence, subtract the value of the second term from the value of the first term to find the common difference. Then, use the formula an = a1 + (n - 1)d, where a1 is the first term and d is the common difference.
Step-by-step explanation:
To find the rule for the nth term of an arithmetic sequence, we need to first find the common difference of the sequence. The common difference is the difference between any two consecutive terms. We can find the common difference by subtracting the value of the second term from the value of the first term. In this case, a6 - a2 = 27 - 129 = -102. Now that we have the common difference, we can write the rule for the nth term as an = a1 + (n - 1)d, where a1 is the first term and d is the common difference. In this case, an = 129 + (n - 1)(-102).