In first take make a new relation by using renaming operator and the new relation will contain union of two Boat relation B1 and B2 with selection condition having colour for first as red and colour for second as green
Now make a natural join of this new relation with reserves and then again do the natural join of this result with Sailors relations
and apply projection condition specified as sname
For second part make two relations by renaming operator where new relations will contain natural join of reserves with boats which will have green colour
and another table which will have natural join of reserves with boats which will have green colour
.Now intersect these tow relations and natural join the result with sailors relation and apply projection operator with sname