math 30-1 #6-7permutations and combinations

6. Two couples are trying to buy tickets to a nearly sold-out concert. The seat map shows the section they plan to sit in, where black seats are already sold. If each couple plans to sit beside each other in the same row, how many different ways can the two couples arrange their seating? 7. Algebraically determine the value of n for , P = 2(,C.)