Table: brunei_demographics_2
Columns: average_population_x_1000
live_births
deaths
natural_change
crude_birth_rate_per_1000
crude_death_rate_per_1000
natural_change_per_1000

Question: Which Crude death rate (per 1000) has Deaths of 768, and a Crude birth rate (per 1000) smaller than 29.7?
SQL: SELECT MIN("crude_death_rate_per_1000") FROM brunei_demographics_2 WHERE "deaths" = '768' AND "crude_birth_rate_per_1000" < 29.7