I have 2 files and i have to calulate mean of numbers stored in these files

like :

file 1: x y
12.33 12.33
23.44 344444

file 2: x y
122.33 344.55
122.33 344.55

add 00 location of file 1 to 00 location of file 2 and finding mean .

so how can i approached it??