Suppose I have 6 shirts, 4 ties, and 3 pairs of pants. If an outfit requires a shirt and pants, and can either have a tie or not have a tie, how many outfits can I make?
6x3=18 so 18 outifts with shirt and pants. Now, 18x4=72 so 72 outfits with ties. Lastly, 18 outifts without ties and 72 outfits with ties. 72+18=90 outifts.
