.
Consider positive integer numbers x and y.
When y is divided by x the remainder is 29. When y is divided by x/2, the remainder is 13. Determine x.
~~~~~~~~~~~~~~~
You just saw the solutions by other tutors suggesting to use trial and error method.
Meanwhile, the problem admits simple straightforward pure mathematical solution based on reasoning, ONLY.
In my opinion, it is the most suitable solution for this problem.
And I am 179% sure that this solution is what you are seeking for.
(1) Consider the statement "When y is divided by x the remainder is 29".
It means that there is an integer number "n" such that
y = nx + 29, 29 < x. (1)
(2) Consider next statement "When y is divided by x/2, the remainder is 13".
It means that there is an integer number "m" such that
y = , 13 < . (2)
(3) From equations (1) and (2) we have
nx + 29 = , x > 29
or, equivalently
2nx + 58 = mx + 26, x > 29
58 - 26 = mx - 2nx, x > 29
32 = (m - 2n)x, x > 29 (3)
(4) Thus, the integer number x is a divisor of the number 32, and x > 29.
But the only such integer is x = 32.
The problem is just solved, and the ANSWER is: the number " x " is 32.