The task is to generate the correct answer for a given math problem.

Input: Consider Input: Problem: which number can we add to 425897 to get a number exactly divisible by 456 ?

Output: 7

Input: Consider Input: Problem: if the sides of a cube are in the ratio 5 : 3 . what is the ratio of their diagonals ?

Output: 5 : 3'

Input: Consider Input: Problem: the speed of a car is 65 km in the first hour and 45 km in the second hour . what is the average speed of the car ?
Output: 55 kmph