Question 15 • Precalculus
The rows contain 18, 17, 16, and so on, decreasing by 1 each time. After 15 rows, the last row has 18 − 14 = 4 boxes. The total is the sum of 15 terms from 18 to 4: (18 + 4) × 15 ÷ 2 = 165 boxes, so the correct choice is A, 165.
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