Question

A number consists of two digits whose sum is 5. If we add 9 with the number, the digits in the number are interchanged.

Answer 1

Let us assume, x and y are the two digits of the two-digit number
Therefore, The two-digit number = 10x + y and reversed number = 10y + x
Given:
x + y = 5 -----------1
Also given:
10x + y +9 = 10y + x
9y - 9x = 9
y - x = 1 or -x + y = 1 ----------2
Adding equation 1 and equation 2
2y = 6
y = 3
Therefore, x = 5 - y = 5 - 3 = 2
Therefore, the two digit number = 10x + y = 10*2 + 3 = 23

Answer 2

Answer:

Let us assume, x and y are the two digits of the

two-digit number

Therefore, The two-digit number = 10x + y and

reversed number = 10y + x

Given: x + y = 5

Also given:

-1

10x + y +9 = 10y + x

9y-9x = 9

y - x = 1 or -x + y = 1 ----------2

Adding equation 1 and equation 2

2y = 6

y = 3

Therefore, x = 5-y=5-3=2 Therefore, the two digit number = 10x + y = 10*2 +3=((23))