What is # Eng., when Outside Diameter, Main Passenger Deck is "inches (m)", and when Maximum Metric MTOW is "231.3 tons"?
CREATE TABLE "widebody_specifications" (
  "model" text,
  "eis_final_prod_year" text,
  "num_eng" real,
  "maximum_metric_mtow" text,
  "outside_diameter_main_passenger_deck" text
);
SELECT "num_eng" FROM "widebody_specifications" WHERE "outside_diameter_main_passenger_deck"='inches (m)' AND "maximum_metric_mtow"='231.3 tons';