Problem 3. (20 points) Consider a database consisting of the following relations: SAILORS(Sid, Sname, Rating, Age) RESERVED(Sid, Bid, Day) BOATS(Bid, Bname, Color) For each of the following retrieval request, write a relational algebra expression. (1) Retrieve the names of the sailors who have reserved a red or green boat. (2) Retrieve the names of the sailors with age over 30 who have not reserved a red boat. (3) Retrieve the colors of the boats reserved by Smith. 4) Retrieve the ids of the sailors with a rating over 6 who have reserved a boat. (5) Retrieve the names of the sailors who have reserved all boats