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Question

By interchanging the given two numbers (not digits) which of the following equation will NOT be correct?

9 and 7

I. 9 x 2 + 7 -  6 $\div$ 3 = 21

II. 7 x 3 + 9 - 8 $\div$ 2 = 30

The correct answer is

Neither I nor II

We are given two equations and need to determine after interchanging the numbers 9 and 7 which equation will NOT be correct.

Let's examine each equation after interchanging 9 and 7:

  1. Equation I: \(9 \times 2 + 7 - 6 \div 3 = 21\)
    After interchanging, we get: \[7 \times 2 + 9 - 6 \div 3 = 21\]
    Calculation: \(= 14 + 9 - 2 = 21\)
    This equation holds true after interchanging 9 and 7.
  2. Equation II: \(7 \times 3 + 9 - 8 \div 2 = 30\)
    After interchanging, we get: \[9 \times 3 + 7 - 8 \div 2 = 30\]
    Calculation: \(= 27 + 7 - 4 = 30\)
    This equation also holds true after interchanging 9 and 7.

After verifying both equations with interchanged numbers, they remain true. Thus, both equations I and II are correct when numbers 9 and 7 are interchanged.

Hence, the answer is Neither I nor II will NOT be correct.

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