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

Example Input: Problem: set s contains exactly 10 numbers and has an average ( arithmetic mean ) of 6.2 . if one of the numbers in set s is increased by 7 , while all other numbers remain the same , what is the new average of set s ?
Example Output: 6.

Example Input: Problem: two trains of length 100 meters and 200 meters are 450 meters apart . they are moving towards each other on parallel tracks , at speeds of 90 km / h and 72 km / h . after how many seconds will the trains meet ?
Example Output: 10

Example Input: Problem: a train is running at a speed of 40 km / hr and it crosses a post in 22.5 seconds . what is the length of the train ?
Example Output:
250 metre