Question

29. A number has two digits whose sum is 6.
On adding 18 to the number, its digits are
interchanged. The number is
(a) 23
(b) 24
(c) 26 (d) 25​

Answer 1

Let the number = 10x + y

Given :

A number has two digits whose sum is 6.

On adding 18 to the number

Answer :

x+y = 6

10x + y +18 = 10y + x

(10y + x) - (10x +y) =18

9y - 9x = 18

y - x = 18/9

y - x = 2

(x +y) - (y-x) = 6 - 2

2x = 4

x = 4/2

x = 2

x + y = 6

2+y = 6

6-2 =y

y = 4

The number = 10x + y

= 10×2 + 4

= 24

Hope this will help.....