Combining Lookup function and Sum function

[Cameron]

I am trying to use the lookup function to find all values in a spreadsheet
matching "D" then returning the value to the left of it. I would like the
function to sum all the values before it is returned. Is this possible to do
in one step?

 

[T. Valko]

Is this what you had in mind:

...........A..........B
1........5..........X
2........3..........D
3........7..........D
4........2..........Y
5........5..........D

=SUMIF(B1:B5,"D",A1:A5)

Result = 15