Where the height range is higher than 20000.0 and the shell weight is 12.5, what is the time to feet ratio at 25 degrees?
CREATE TABLE "table1_16439764_1" (
  "gun" text,
  "m_v_ft_s" real,
  "shell_lb" text,
  "time_to_ft_m_at_25_seconds" text,
  "time_to_ft_m_at_40_seconds" text,
  "time_to_ft_m_at_55_seconds" text,
  "max_height_ft" real
);
SELECT "time_to_ft_m_at_25_seconds" FROM "table1_16439764_1" WHERE "shell_lb"='12.5' AND "max_height_ft">20000.0;