Simplify the following text for a Grade 7 native English-speaking person.
Original: Peter Schidlof ( July 9 , 1922 â `` August 16 , 1987 ) was an Austrian-British violist and co-founder of the Amadeus Quartet .
Simplified: Peter Schidlof ( July 9 , 1922 â `` 1987 ) was an Austrian-British violist . He played the viola in the Amadeus Quartet .