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

Example Input: Problem: the average weight of a group of boys is 30 kg . after a boy of weight 45 kg joins the group , the average weight of the group goes up by 1 kg . find the number of boys in the group originally ?
Example Output: 14

Example Input: Problem: on a certain road , 10 % of the motorists exceed the posted speed limit and receive speeding tickets , but 20 % of the motorists who exceed the posted speed limit do not receive speeding tickets . what percent of the motorists on that road exceed the posted speed limit ?
Example Output: 12.5 %

Example Input: Problem: there are 280 doctors and nurses at a hospital . if the ratio of doctors to nurses is 5 to 9 , how many nurses are at the hospital ?
Example Output:
180