Question
After interchanging × with ÷ , and 7 with 4 , which of
the following equations becomes correct?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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