Question
After interchanging '- ' and '+ ' , 6 and 7 , which of
the following equations becomes correct?Solution
1. 40 + 6 × 13 – 7 × 2  = 104 ⇒ 40 – 7 × 13 + 6 × 2 ⇒ 40 – 91 + 12 ⇒ - 39  ≠104 2. 35 – 7  ×  3 + 6 = 45 ⇒ 35 + 6 × 3 – 7 ⇒ 35 + 18 – 7 ⇒ 46 ≠45 3. 6 ×  14  + 36 ÷ 7 – 2  = 92 ⇒ 7 × 14 – 36 ÷ 6 + 2 ⇒ 98 – 6 + 2 ⇒ 94 ≠92 4. 38 – 6 × 13 + 66  ÷ 7 = 118 ⇒ 38 + 7 × 13 – 66 ÷ 6  ⇒ 38 + 91 – 11  ⇒ 118 = 118 Hence, option 4 is correct.
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