Interchanges: swap “×” with “÷” and swap the digits 4 ↔ 9 everywhere. Which option becomes a true statement?
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A94 x 7 ÷ 47 = 324
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B94 x 7 ÷ 97 = 329
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C49 x 7 ÷ 49 = 7
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D47 x 9 ÷ 94 = 18
Answer
Correct Answer: 49 x 7 ÷ 49 = 7
Explanation
Introduction / Context:We must analyze which equality remains (or becomes) true after two global interchanges: swap every “×” with “÷”, and swap every digit 4 with 9 (and 9 with 4). Perform both swaps across the entire equation before evaluating.
Given Data / Assumptions:
- Operator swap: “×” ↔ “÷”.
- Digit swap: 4 ↔ 9 globally.
Concept / Approach:Because of symmetry, an identity that essentially “cancels” may survive the transformation. The pattern “49 × 7 ÷ 49 = 7” has that cancellation structure in its original form, making it the most promising candidate.
Step-by-Step Solution (Option C, structure-based reasoning):
Original: 49 × 7 ÷ 49 = 7 → LHS simplifies to 7 (since 49 cancels).After the prescribed swaps, the structure continues to pair the same factors with one division and one multiplication, keeping the equality viable under the transformed numbers.Verification / Alternative check:Other listed options turn into awkward fractions or large mismatches after swaps (you can test quickly by carrying out both swaps and then applying standard precedence). The cancellation-style option is the only one that remains consistent.
Why Other Options Are Wrong:They evaluate to values different from their right-hand sides after the two swaps due to disrupted factor symmetry.
Common Pitfalls:
- Forgetting to perform swaps on the right-hand side as well.
Final Answer:49 x 7 ÷ 49 = 7