CREATE TABLE table_name_4 (gothic_letter VARCHAR, proto_germanic_origin VARCHAR)

Which Gothic Letter has Proto-Germanic origin of / /; /b/?
SELECT gothic_letter FROM table_name_4 WHERE proto_germanic_origin = "/ɸ/; /b/"
SELECT "gothic_letter" FROM "table_name_4" WHERE "/ɸ/; /b/" = "proto_germanic_origin"