Marcella has 20 pairs of shoes. If she loses 9 individual shoes, what is the greatest number of matching pairs she could have left? Choose the correct choice:
A) 21  B) 20  C) 19  D) 16  E) 15

Rationale: "marcella has 20 pairs of shoes and loses 9 shoes . to minimize the loss of identical pairs of shoes we want marcella to lose as many identical pairs as possible . this would yield 4 identical pairs and 1 additional shoe ( destroying 5 pairs of shoes ) . the 20 pairs of shoes minus the 5 ' destroyed ' pairs yields 15 pairs that still fulfill the requirements . answer : e"
Answer: E