Qual taxa de mortalidade bruta (por 1000) tem 768 mortes e uma taxa de natalidade bruta (por 1000) menor que 29,7?
CREATE TABLE table_name_51 (crude_death_rate__per_1000_ INTEGER, deaths VARCHAR, crude_birth_rate__per_1000_ VARCHAR)
SELECT MIN(crude_death_rate__per_1000_) FROM table_name_51 WHERE deaths = "768" AND crude_birth_rate__per_1000_ < 29.7