user: Question: Name the total number of frequency Mhz with class of d and call sign of k201bm and ERP W less than 74
Columns: ['Call sign', 'Frequency MHz', 'City of license', 'ERP W', 'Class', 'FCC info']
Types: ['text', 'real', 'text', 'real', 'text', 'text']
Sample row: ['K201BM', 88.1, 'Canadian, Texas', 74.0, 'D', 'FCC']
SQL:

assistant: SELECT COUNT("Frequency MHz") FROM "Table" WHERE "Class" = 'd' AND "Call sign" = 'k201bm' AND "ERP W" < 74.0;