Daily Duplication between two sites based on Monthly data

Given two sites (say Yahoo and MSN) having monthly numbers for:
* "total monthly unique visitors (000)" (MUV)
* "average daily unique visitors (000)" (DUV)
* "average usage days per visitor" (ADPUV)
* "days in month" (DAYS)
* "total monthy duplicate unique visitors (000)" (MDUP)

We'd like to calculate the "average daily duplicate unique visitors (000)" (DDUP) between the two sites.
We believe that there is a statistical solution based on ADPUV and DAYS for this problem, but we are at a loss for a solution.

For Yahoo:
MUV = 113209
DUV = 37774
ADPUV = 10.0

For MSN:
MUV = 58646
DUV = 18276
ADPUV = 9.3

Mutual Varaibles:
MDUP = 28103
DAYS = 30

Expected Results:
DDUP = 4442