#11 Each roll is 9' long, length of each roll = 9' * (12"/foot) = 108" Each ribbon piece = 15", so number of ribbons per roll =108/15=7 with 3" left over, which is assumed not possible to be joined with other pieces. Therefore, with 5 rolls, there are 7*5=35 pieces of ribbon, with 5 pieces or 3" left over.