CREATE TABLE table_name_78 (karen_handel VARCHAR(255), poll_source VARCHAR(255), john_oxendine VARCHAR(255))
What is Karen Handel polling at in the Insideradvantage poll where John Oxendine is at 15%?
    
SQL: SELECT karen_handel FROM table_name_78 WHERE poll_source = "insideradvantage" AND john_oxendine = "15%"