Creed have sold well over 34 million albums from their 3 albums. They were the most successful band in the world for 8 years.
The RIAA just stopped reporting on each album's sales and just gave the total of the three. Human Clay sold well over 11 Million copies (which was the last count from the RIAA) individually by now.
So we can guess that MOP sold 8 Million, Human Clay Sold 14 and Weathered Sold 12 ok. Which equal 34 million.