=SUMPRODUCT(--(A1:A24="Ted"),--(B1:B24="May"),--(C1:C24))
column a <Person, column b <Month, Column C <Cost

I need to total all of Ted's Costs for May.
But Now I need to do it for the quarter.
So for say January, Feburary, March and April, four month blocks.
How would I tweak Sumproduct to do that ...
All cost for those four months.