user: Question: What is the total number of the ERP W with a call sign of w242ak?
Columns: ['Call sign', 'Frequency MHz', 'City of license', 'ERP W', 'Class', 'FCC info']
Types: ['text', 'real', 'text', 'real', 'text', 'text']
Sample row: ['W254AI', 98.7, 'Auburndale, Florida', 55.0, 'D', 'FCC']
SQL:

assistant: SELECT SUM("ERP W") FROM "Table" WHERE "Call sign" = 'w242ak';