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

Example Input: Problem: the average of first six prime numbers greater than 20 is ?
Example Output: 3

Example Input: Problem: a jeep takes 9 hours to cover a distance of 480 km . how much should the speed in kmph be maintained to cover the same direction in 3 / 2 th of the previous time ?
Example Output: 35 kmph

Example Input: Problem: two trains of equal lengths take 8 sec and 15 sec respectively to cross a telegraph post . if the length of each train be 120 m , in what time will they cross other travelling in opposite direction ?
Example Output:
10