Question

    After interchanging "×" and "÷", "7" and "4", which of

    the following equations becomes correct?
    A 21 × 4 + 7 ÷ 5 = 24 Correct Answer Incorrect Answer
    B 35 × 4 + 7 ÷ 2 = 20 Correct Answer Incorrect Answer
    C 7 ÷ 4 + 15 × 5 = 35 Correct Answer Incorrect Answer
    D 140 × 4 + 20 ÷ 7 = 100 Correct Answer Incorrect Answer

    Solution

    1. 21 ×  4 + 7  ÷ 5 = 24 ⇒ 21 ÷ 7 + 4 × 5 ⇒ 3 + 20 ⇒ 23 ≠ 24 2. 35 ×  4 + 7 ÷ 2 = 20 ⇒ 35 ÷ 7 + 4 × 2 ⇒ 5 + 8 ⇒ 13 ≠ 20 3. 7 ÷ 4 + 15 × 5 = 35 ⇒ 4 × 7 + 15 ÷ 5 ⇒ 28 + 3 ⇒ 31 ≠ 35 4. 140 × 4 + 20 ÷ 7 = 100 ⇒ 140  ÷ 7 + 20 × 4 ⇒ 20 + 80 ⇒ 100 = 100 Hence, option 4 is correct.

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