SUMIF where multiple criteria are true?

I need to learn how return the sum of only those values at C1:C100 for which:
1.) labels at A1:A100 = (match) a label entered at another cell location
AND
2.) values at B1:B100 = value returned by function at another cell location
In word form I imagine such a function to read something like: SUM C1:C100 where labels A1:A100 = label at (cell location) and where values B1:B100 = result at (cell location)

I've exhausted my meager skills and would very much appreciate some guidance. For those who might be so inclined:
A1:A100 contains a multitude of labels; some of which appear repeatedly.
B1:B100 contains various values associated with the labels in column A.
C1:C100 contains other various values also associated with the labels in a column A.

I will manually enter one of the two criteria (the label) and the other (the value) is returned by an array function.

Thanks in advance for any help.

Try using this setup:

=SUMPRODUCT(--(A1:A100=F1),--(B1:B100=G1),(C1:C100)

Note in my example, I used F1 and G1 to represent the cells that you are checking against. Change this as necessary