Matt Bowlby

I have a housing database which lists individual housing units (Unit) with the area (Area 1, Area 2, Area 3, etc.) the building is located and the number of families (1, 2, 3, etc.) housed in the building. I need to create a calculation that gives the total number of families that are associated with Area 1. So, if I have UNIT AREA FAMILIES 1 1 1 2 1 3 3 1 2 4 2 1 5 3 2 6 3 2 So, the total number of families in Area 1 is equal to 6. How do I calculate this? Thank you, Matt.