Question

The tens digit in a two digit number is twice the units digit.If 18 is subtracted from the number,the digits are reversed.find the number.

Answer 1

Let the units digit=x
Then the tens digit=2x

Number is 10×(2x)+x

On reversing ,
New number 10(x)+2x

Given,
10×(2x) +x -18=10×(x)+2x

20x+x-18=10x+2x
21x-18=12x
9x=18
x=2

The original number is
10×(2x)+x
=10(2×2) + 2
=42