Adding up donated hours

[Guest]

I've begun a spreadsheet to track donated hours for a project. Some people
have donated a specific number of hours; others have donated a number of
hours multiplied over a 3-month period. I need to add both columns to get a
somewhat clearer count of the total number of hours donated. Is this clear
enough?

Example:

Column A - Name
Column B - Number of Hours Donated
Column C - X (if they've donated x number of hours each week)
Column D - =SUM(B*C)

I need to filter out Column B from D if C=X. It seems so simple, but I
don't know the right formula!

 

[Bernard Liengme]

If there are number in every pair of cells (A and B) then
=SUMPRODUCT(B1:B100,C1:C100)
But it sounds as if you have some B's without C's; these will be treated as
zeros
Any chance the blank could be made 1?
best wishes

 

[Guest]

I changed the blanks to "1" and got the same result as my "test" (adding up a
few of the cells manually). Thank you!