Find the sum of the first 70 terms of the sequence –6, –3, 0, 3, 6, ...

The sequence is arithmetic: it starts at −6 and increases by 3 each term. The 70th term is −6 + 69(3) = 201, so the sum is 70(−6 + 201) ÷ 2 = 6,825. The correct choice is b, 6,825.

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