user: Question: Frequency MHz of 88.7 had what average erp w?
Columns: ['Call sign', 'Frequency MHz', 'City of license', 'ERP W', 'Class', 'FCC info']
Types: ['text', 'real', 'text', 'real', 'text', 'text']
Sample row: ['KJRL', 105.7, 'Herington, Kansas', 12500.0, 'C3', 'FCC']
SQL:

assistant: SELECT AVG("ERP W") FROM "Table" WHERE "Frequency MHz" = 88.7;