BEx Query Issue

Hello, I have data in my DSO like this:

Customer      CALMONTH/Year      Quantity
101                 01/2014                      10
101                 02/2014                      25
101                 03/2014                      36
101                 04/2014                      45
101                 05/2014                      90
101                 06/2014                      10
101                 07/2014                      20

There is a Z field in 0CUSTOMER which stores some number so there i have data like this in master data:

0CUSTOMER      ZDAYS
101                      25

What user wants to see in the report is since Customer 101 has 25 days and the report is run today "15th May 2014". i want to add 25 days to 15th may which will fall under June, 2014 bucket right, so then I want the final result to show the data from the beginning until June, 2014.

Customer      Quantity
101                 216

Can i do this at reporting level?

Please let me know.
Thanks.