Difficulty: Easy
Correct Answer: 120
Explanation:
Introduction / Context:
This is a steady decrement where each subtraction is 9 less than the previous subtraction. Such “step-down by a fixed amount” patterns are quick once spotted.
Given Data / Assumptions:
Concept / Approach:
Subtractions are 81, 72, 63, 54 (each reduces by 9). The next subtraction is 45.
Step-by-Step Solution:
Verification / Alternative check:
Adding 45 back to 120 returns 165, preserving the −9 ladder.
Why Other Options Are Wrong:
Common Pitfalls:
Assuming constant subtraction (not the case); here the subtraction itself decreases linearly.
Final Answer:
120
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