Summing data by Text criteria (Please help!!!!!!)

I have a large database that I work with. My co-workers enter some of our data with a lower case y's (example yTrade) and z's (example zLink) and all others upper case letters (example Canada). My first column is the date, the third column is the lower case y's and z's and my fifth column is the number of buys. I would like to sum the number of buys in my fifth column from all of my y's and z's by date and exclude all the buys from the uppercase companies.

Thanx in advance,
Tito