Marcella has 23 pairs of shoes. If she loses 9 individual shoes, what is the greatest number of matching pairs she could have left?
Answers.
A) 21
B) 20
C) 19
D) 18
E) 15

Rationale: marcella has 23 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 23 pairs of shoes minus the 5 ' destroyed ' pairs yields 20 pairs that still fulfill the requirements . answer : d
Answer: D