Difficulty: Easy
Correct Answer: 11 8
Explanation:
Introduction / Context:
This arithmetic progression decreases steadily by a constant amount. Accuracy in repeated subtraction is all that is needed.
Given Data / Assumptions:
Concept / Approach:
Extend by subtracting 3 sequentially from the last term provided.
Step-by-Step Solution:
Verification / Alternative check:
Rebuild tail: 20, 17, 14, 11, 8 maintains −3 each time.
Why Other Options Are Wrong:
Common Pitfalls:
Miscalculating one of the subtractions when working quickly.
Final Answer:
11 8
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