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

Example Input: Problem: a theater box office sold an average ( arithmetic mean ) of 65 tickets per staff member to a particular movie . among the daytime staff , the average number sold per member was 75 , and among the evening staff , the average number sold was 60 . if there are no other employees , what was the ratio of the number of daytime staff members to the number of evening staff members ?
Example Output: 1 : 2

Example Input: Problem: find the area of a parallelogram with base 10 cm and height 20 cm .
Example Output: 200

Example Input: Problem: 39 persons can repair a road in 12 days , working 5 hours a day . in how many days will 30 persons , working 3 hours a day , complete the work ?
Example Output:
26