CREATE TABLE "armament" (
  "name" text,
  "country" text,
  "displacement_tons" real,
  "armament" text,
  "weight_of_discharge" text,
  "speed" text
);

Question: How much Displacement (tons) has an Armament of 2 x -inch (mm), 16 x -inch (mm)?
SQL: SELECT COUNT("displacement_tons") FROM "armament" WHERE "armament"='2 x -inch (mm), 16 x -inch (mm)';