You can have SAP do the calculation for you in 2 ways: 1. Use Network activity elements, or 2. Use Unit costing.
1. Under the Network Activity create a series of Network Activity Elements. NWA elements are very similar to network activities except they adopt the dates of the NWA.
Plan your different Activity Type/Work Center combinations (locations) with correct work quantities on each NWA element. This will give you the exact number you wish. Using NWA elements allows you to use them for workforce planning and to track actual charges agianst them.
OR
2. Make the network activity a General Cost activity (key PS03) and click on the calculator icon next to the value. On the Unit Costing screen you can list the cost center/activity type/qualtity combinations. SAP will do the math for you.