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

[EX Q]: Problem: arjun started a business with rs . 20,000 and is joined afterwards by anoop with rs . 80 , 000 . after how many months did anoop join if the profits at the end of the year are divided equally ?
[EX A]: 9

[EX Q]: Problem: in a university the average age in an arts class is 21 and average age in technical class is 18 . what is the age average of university if there are 8 arts classes and 5 technical classes ?
[EX A]: 19.85

[EX Q]: Problem: the total number of digits used in numbering the pages of a book having 369 pages is
[EX A]:
999