Question

x has 3 digits. the tens digits is half the hundreds digits. the number is odd.the sum of the digits is 9

Answer 1

Let the tens digit be x. Then the hundreds digit is 2x. The sum of these two digits is 3x, and that has to be less than 9, so x must be less than 3 - that is, the tens digit must be 1 or 2.

So we might have:

42U or 21U

where U is the Units digit.

The digits add to 9, so it has to be

423 or 216

But we are told that the answer is odd, and only one of those is odd...

Answer 2

x + 2x = 3x
solve this first
where 3x < 9
3/3 x < 9/3 divide
both sides by 3
1x < or = 3 plug in 3 into the equation.
3 + 3*2 = 3*3

3 + 6 = 9