Age field on task table

Hi All ,

I want to create a field which calculates age of the open tickets on the task table . I want it on Task table so that it can be used to calculate the age of all the tickets - incident , problem ,request etc.

How this can be done ? After creating this field it has to be used for reporting on task table , means all the open tickets -incident , problem ,request etc. ( ages ) can be represented in the report.

Thanks & Regards,

Snehal Khare