SELECT COUNT(incumbent) FROM table_1341690_21 WHERE candidates = "Paul Tsongas (D) 60.6% Paul W. Cronin (R) 39.4%"
Berapa kali kandidat Paul Tsongas (D) 60,6% Paul w.Cronin (R) 39,4%?
CREATE TABLE table_1341690_21 (incumbent VARCHAR, candidates VARCHAR)