Please help solve

3. When permutations and combinations collide! Thomas has 10 pictures of family and 8 pictures of friends that he'd like to put up on a shelf. The shelf can't fit all the photos; it can only fit seven photos in a straight line. He is going to pick four family photos and 3 friend photos, and then arrange them. How many possibilities exist for him choosing AND arranging the photos? SUMMARY: Does order count? yes. No. Use Permutations Use Combinations it A tins > OL,or Arranging r of n Arrangements Selecting exactly Number of selection distinct objects with some r items from n: is not defined exactly: Use: nPr identical objects: Use: n Cr Divide by repeats Use: 2" - 1 Check with teacher, then try 3.3 HW pg 120 #