Table schema:
CREATE TABLE table_name_37 (watts INTEGER, city_of_license VARCHAR, class VARCHAR, frequency VARCHAR)

Question: How many Watts has a Class of a, and a Frequency of 91.5 fm, and a City of license of elkhart, kansas?
SQL: SELECT MIN(watts) FROM table_name_37 WHERE class = "a" AND frequency = "91.5 fm" AND city_of_license = "elkhart, kansas"