Simplify the following text for a Grade 7 native English-speaking person.
Original: Keselowski finished 16th . Shortly afterwards , he was called by car owner Dale Earnhardt , Jr to drive his # 88 United States Navy Chevrolet for JR Motorsports for the rest of the year in the Busch Series , posting five top-ten finishes .
Simplified: After driving for a few teams , Dale Earnhardt , Jr. called Keselowski asking him to drive his # 88 United States Navy Chevrolet for JR Motorsports for the rest of the year .