Answer:
Joint profits are maximized when Carnival picks $260 and Royal Caribbean picks $260.
Explanation:
                         Royal Caribbean
                  high price          low price
                 $9,000 /          $14,720 /
       high price         $9,000           $1,620
Carnival
       low price   $1,620 /          $8,320 /
                        $14,720           $8,320
Carnival's dominant strategy is to charge a low price ($260) because it yields the highest profits = $14,720 + $8,320 = $23,040.
Royal Caribbean's dominant strategy is to charge a low price ($260) because it yields the highest profits = $14,720 + $8,320 = $23,040.
Since both companies have the same dominant strategy, a Nash equilibrium exists when they both charge a low price ($260).