$(10$ points$)$ Consider the following database schema

Flight $($Source$,$ Destination$)$

Hub $($City$)$

$!(,)$: $(,),(),(,),()$

$"(,)$: $(,),(),(,)$

$($a$)(5$ points$)$ Use the conjunctive query containment algorithm to show that $!$

$"$

$($b$)(5$ points$)$ Unfold the following query

$$# $(,)$: $!(,),"(,)$