Refer to the following relational schema for the following questions:

Player $($player$\_$did, player$\_$name, level, League$\_$id$)$

League $($league$\_$id$,$ leage$\_$name, leader$\_$id$,$ creation$\_$date$)$

Character $($character$\_$ld$,$ character$\_$name, class, player$\_$id$)$

Inventory $($character$\_$id$,$ item$\_$id$,$ quantity$)$

Wrte queries using Relational Algebre operations $($using the operators $($select$),($project$),*($natural join$),$ and aggregate functions$)$ to answer each of the following questions.

List the names of the players and the names of the leagues cach player belongs to$.$

Find the average quantity of each item in the inventory.

List players who are at level $50$ or higher, along with the names of their leagues.

Find the IDs of the players who do not have any characters.

Find the names of the characters owned by the player with the ID $"$P$123."$