What 1st leg has 52-70 as the agg.?
CREATE TABLE "round_of_16" (
  "team_1" text,
  "agg" text,
  "team_2" text,
  "1st_leg" text,
  "2nd_leg" text
);
SELECT "1st_leg" FROM "round_of_16" WHERE "agg"='52-70';