Final answer:
The number of Eminem's albums in the top 20 Hip Hop albums of all time is subjective and varies by source. Eminem commonly has multiple albums, such as 'The Marshall Mathers LP', mentioned in these lists, but a definitive number is not provided here.
Step-by-step explanation:
The question of how many albums by Eminem are considered in the top 20 Hip Hop albums of all time is subjective and can vary depending on the source. However, taking into account the various rankings and the critical acclaim Eminem's work has received over the years, he is often featured with multiple entries in such lists. His album 'The Marshall Mathers LP' is frequently cited as one of his most influential, and it is not uncommon to find 'The Eminem Show' and 'Slim Shady LP' making these lists as well.
It's important to note that while Eminem is a highly regarded artist in hip-hop, a definitive answer requires consulting specific rankings as these lists can change over time and are often influenced by both critical assessment and public opinion. As of my last update, there is no exact number provided for how many of Eminem's albums are in the top 20 of all time.