Who is the longest serving coach from year 1970 to 1980. List the coach ID and the team(s) he served.
1970 to 1980 refers to year between 1970 and 1980; longest serving coach Max(Count(coachID)); team(s) he served refers to tmID
SELECT coachID, tmID FROM coaches WHERE year BETWEEN 1970 AND 1980 ORDER BY stint DESC LIMIT 1