80 ? 860 1550 2440 3530\nOptions:\n(A) 370\n(B) 840\n(C) 750\n(D) 860\n(E) 960
Let’s work this out in a step by step way to be sure we have the right answer.
(A)
10^2 - 20 = 80\n20^2 - 30 = 370\n30^2 - 40 = 860\n40^2 - 50 = 1550\n50^2 - 60 = 2440\n60^2 - 70 = 3530.

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So, the answer is (A)