Question

In a two-digit number, the units digit is twice the tens digit. If the number is doubled, it will be 9 more than the number reversed. Find the number. :) Thanks!

Answer 1

10(2x)+x
21x is the original number

12x is the reversed number
24x is the reversed then doubled number

Set up an equation:
24x=21x+9
3x=9
x=3

The original number is 63 and the reversed number is 36, which then is 72 when doubled.

Answer 2

We know that the ones digit is 2x the tens digit. The number has to be two digits, so this leaves the options of 12, 24, 36, and 48.

Next, we double each number.
12 x 2 is 24
24 x 2 is 48
36 x 2 is 72
48 x 2 is 96

And subtract 9 from each of those. 15, 39, 63, and 87.

63 backwards is 36. The number you are looking for is 36. :)