CREATE TABLE table_68547 ("Year" FLOAT, "Chassis" CLOB, "Engine" CLOB, "Start" CLOB, "Finish" CLOB, "Entrant" CLOB)

What is the start of Offy engine and in 1972?
SELECT "Start" FROM table_68547 WHERE "Engine" = 'offy' AND "Year" = '1972'
SELECT "Start" FROM "table_68547" WHERE "Engine" = 'offy' AND "Year" = '1972'