Previous Year Questions

We are tasked with identifying two numbers to interchange in the equation:

48÷3+12 X 4−6 X 7+21=27

Let's solve it step by step.

Step 1: Original equation

The equation is:

48÷3+12 X 4−6 X 7+21

Apply BODMAS (order of operations: Brackets, Orders, Division/Multiplication, Addition/Subtraction).

Step 2: Interchange numbers

Now, consider the given options and interchange the numbers as specified. After each interchange, recalculate the equation.

Option 1: Interchange 3 and 4

If 3 and 4 are interchanged, the equation becomes:

48÷4+12 X 3−6 X 7+21

Recalculate:

1) 48÷4=12

2) 12 X 3=36

3) 6 X 7=42

Substitute:

12+36−42+21

Step-by-step:

1) 12+36=48

2) 48−42=6

3) 6+21=27

This matches the required result of 27.

As option (a) satisfies so no need to check other options.