What year had an Allison B400R transmission and a model of BRT?
CREATE TABLE "buses" (
  "fleet_num" text,
  "year" real,
  "manufacture" text,
  "model" text,
  "length_ft" real,
  "engine" text,
  "transmission" text
);
SELECT "year" FROM "buses" WHERE "transmission"='Allison B400R' AND "model"='BRT';