Using CountIf based on multiple criteria

I am not very familiar with using the countif formula and I have a spreadsheet that is used to calculate the number of people who show up for a research project. I need to be able to quickly view the number of people who have signed in based on ***, race, education and age. So I will need to create a cell that counts the number of "X"s in column A when the number in column E<35, and then have another cell that counts the number of "X"s in column A when column F=M, and then have another cell that counts the number of "X"s in column A when column F=HS, and so on.


Any help is greatly appreciated.