Complex sentence: "Rehab" entered the US "Billboard" Hot 100 chart on November 22,2008, at number 91 and peaked at number 18, making it Rihanna's twelfth US top-twenty single.
Split into simpler sentences: Rehab entered the US "Billboard" Hot 100 chart on November 22,2008, at number 91. It peaked at number 18, and was Rihanna's twelfth US top-twenty single.