Consider the Sailors-Boats-Reserves DB described in the text. S (sid, sname, rating, age) B (bid, bname, color) R(sid, bid, date) Give a Relational Algebra expression for each of the following operations: id 1. Find the colors of boats reserved by Ahmad. 2. Find all sailor id's of sailors who have a rating of at least 8 or reserved boat 103. 3. Find the names of sailors who have not reserved a red boat. A 4. Find the names of sailors who have reserved all boats called BigBoat