Question: Which R 51 O value corresponds to a D 42 O value of R 19?
SQL: SELECT "R 51 O" FROM "2-1104515-3" WHERE "D 42 O" = 'R 19';

Question: What is the value of D 43 O that has a corresponding R 53 + value of R 8?
SQL: SELECT "D 43 O" FROM "2-1104515-3" WHERE "R 53 +" = 'R 8';

Question: What is the value of D 42 O that has an R 53 + value of R 8?
SQL: SELECT "D 42 O" FROM "2-1104515-3" WHERE "R 53 +" = 'R 8';