Question

The sum of the digits of a two digit number is 9 .also 9 times this number is twice the number obtained by reversing the order the digits find the number

Answer 1

Let the digits be x and y, and the number be 10x + y.

Then, x + y = 9 ------ (1)

Also, 9*(10x + y) = 2 * (10y + x)

This gives, 90x + 9y = 20y + 2x

Or 88x = 11y or

y = 8x ---- (2)

Substituting the value of y in eqn. 1, we get

x + 8x = 9 or 9x = 9.

Thus, x = 1 and y = 8*1 = 8.

Thus, the number is 10*1 + 8 = 18.

Answer 2

Here is your solution

Given :-

The sum of the digits of a two digit number is 9

Let
The digits be x and y, and the number be 10x + y.

I. e

x + y = 9 ------ (1)

Then

9×(10x + y) = 2×(10y + x)

90x + 9y = 20y + 2x

88x = 11y

y = 8x ---- (2)

putting the value of y in equation (1.) we get,

x + 8x = 9
9x = 9.
x = 1

y = 8×1 = 8.

Hence

The number is 10x +y = 10×1 + 8 = 18.


Hope it helps you