What's the sum of all values in category 1 when category 3 is equal to 300?
CREATE TABLE "acute_toxicity" (
  "method_of_administration_citation_needed" text,
  "category_1" real,
  "category_2" real,
  "category_3" text,
  "category_4" text,
  "category_5" text
);
SELECT SUM("category_1") FROM "acute_toxicity" WHERE "category_3"='300';