def process_infile
  old_table = CSV.open('file.csv','r')

  old_table.each do |row|
    # copy the row to x
    x = row

    # now that I have copied the row, how do I delete it from the array old_table?

    # find the two other rows that correspond to x and extract them to y and z.
    
    # use data from x, y, z to write a row in the new_table for newfile.csv

  end
end