24. Find the number whose sum of digits equals the difference between 328 and the sought number.
24. Obviously, the desired number is a three-digit number. Let it be $100a + 10b + c$, then $328 - 100a - 10b - c = a + b + c$, which simplifies to $328 = 101a + 11b + 2c$, from which $a = 3$. Therefore, $11b + 2c = 328 - 303 = 25$, from which $b = 1$ and $c = 7$. Thus, the desired number is 317.