sumproduct or sumif function

[Graham]

I have data in columns A:C and would like to sum (Add) the data in A if a
specific criteria in C is met...please assist with a formulae

A B C
100 ? wss
25 cx
50 wss
10 gh

I would like to add values in A were C =wss

 

[Graham]

Hi Guys
I figured it out, =sumif($C$1:$C$4,"wss",A:A),thanx