Find the twenty-seventh term of the arithmetic sequence 21, 18, 15, ...
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Answer: -57
Step-by-step explanation: 21, 18, 15, 12, 9, 6, 3, 0, -3, -6, -9, -12, -15, -18, -21, -24, -27, -30, -33, -36, -39, -42, -45, -48, -51, -54, -57
It is decreasing by 3 each turn. Therefore, the 27th term would be -57.