Question

the ones digit of a two digit number is twice the tens digit when the number formed by reversing the digit is added to the original number the sum is 99 find the original number

Answer 1

let, the tens digit =x
so, ones digit =2x
.•. number= 10x+2x=12x
reverse number= 10×2x+x=20x+x=21x

it is given that,
12x+21x=99
or 33x=99
so, x=3

original number=10x+2x
=30+6
=36 answer.

Answer 2

Let the tens digit be y and the one's digit be x.

Given, x = 2y.

The original number = 10y + x and the reverse number = 10x+y.

Given, 10y + x+10x+y = 99

            10y + 2y + 20y + y = 99

            33y = 99

             y = 3.

The original number = 36.


Hope this helps!