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Question

What will come in the place of ‘?’ in the following equation, if ‘+’ and ‘-‘ are interchanged and ‘×’ and ‘÷’ are interchanged?
5 × 39 ÷ 39 + 39 - 5 = ?

This question was previously asked in
RRB ALP 2025 CBT 2 Wiremen Question Paper (28-Jul-2026) (Shift 2)
The correct answer is
-29

The problem requires solving a given equation after interchanging specific mathematical operators.

Interchanging Operators

The original equation is:

\(5 × 39 ÷ 39 + 39 - 5 = ?\)

The rules for interchange are:

  • '×' is interchanged with '÷'
  • '+' is interchanged with '-'

Applying these interchanges to the original equation, we get the new equation:

\(5 ÷ 39 × 39 - 39 + 5 = ?\)

Solving the New Equation

To find the value of '?', we solve the new equation using the standard order of operations (BODMAS/PEMDAS): Brackets, Orders, Division and Multiplication (from left to right), Addition and Subtraction (from left to right).

  1. Division: Calculate \(5 \div 39\). This is \(\frac{5}{39}\).
  2. Multiplication: Multiply the result by 39. So, \(\frac{5}{39} \times 39 = 5\).
  3. The equation now simplifies to: \(5 - 39 + 5 = ?\).
  4. Subtraction: Calculate \(5 - 39 = -34\).
  5. Addition: Calculate \(-34 + 5 = -29\).

Therefore, the value that comes in the place of '?' is -29.

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Similar Questions

  1. If '+' represents '\(\times\)', '-' represents '+', '\(\times\)' represents '\(\div\)' and '\(\div\)' represents '-', then find the value of the following expression.
    \(6 \div 8 \times 2 - 4\)
  2. Which two signs should be interchanged to correct the given equation?
    \(3 \times 6 + 2 - 4 \div 8 = 13\)
  3. What will come in place of the question mark (?) in the following equation, if '+' and '÷' are interchanged and '-' and 'x' are interchanged?
    312 + 6 x 8 - 21 ÷ 169 = ?
  4. If ‘P’ stands for ‘×’ , ‘Q’ stands for ‘÷’, ‘R’ stands for ‘−’ and ‘S’ stands for ‘+’, then what will come in place of the question mark (?) in the following equation?
    70 Q 2 R 5 P 3 S 18 = ?

Important Questions from Maths Operations

  1. Consider the following arrangement that has some missing letters: abab_b_bcb_dcdcded_d The missing letters which complete the arrangement are

  2. Let A3BC and DE2F be four-digit numbers where each letter represents a different digit greater than 3. If the sum of the numbers is 15902, then what is the difference between the values of A and D?

  3. How many integers are there between 1 and 100 which have 4 as a digit but are not divisible by 4?

  4. Let x, y be the volumes; m, n be the masses of two metallic cubes P and Q respectively. Each side of Q is two times that of P and mass of Q is two times that of P. Let u = m / x and V = n / y. which one or the following is correct?

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