Question

The sum of the digits of a two-digit number is 7. If 2 is subtracted from the number formed by interchanging the digits, the result is double the original number. Find the required number.

Answer 1

Answer:

The required number is 25

Let the digit in the units place be x.

Then, the digit in the tens place is 7 - x.

=> the original number is 10(7 - x) + x.

Then, the number formed by interchanging the digits is 10x + (7 - x)

From the question,

10x + (7 - x) - 2 = 2 {10 (7 - x) + }

Or 9x + 5 = 140 - 18x

Or 18x + 9x = 140 - 5

Or 27x = 135

Or x = 135/27

Or x = 5

So,

the digit in the units place is x = 5

=> the digit in the tens place is 7 - x = 2

Hence,

the required original number is 25

Answer 2

Step-by-step explanation:

The sum of the digits of a two-digit number is 7. If 2 is subtracted from the number formed by interchanging the digits, the result is double the original number. Find the required number