CREATE TABLE table_47910 ("Reservation" TEXT, "Location" TEXT, "1969" FLOAT, "1979" FLOAT, "1989" FLOAT, "2000" FLOAT)

What is the 1979 number for Standing Rock Indian Reservation when the 1989 is less than 54.9?
SELECT SUM("1979") FROM table_47910 WHERE "Reservation" = 'standing rock indian reservation' AND "1989" < '54.9'
SELECT SUM("1979") FROM "table_47910" WHERE "1989" < '54.9' AND "Reservation" = 'standing rock indian reservation'