You are given infinite coins of denominations 5, 7, 9. Which of the following sum CANNOT be achieved using these coins?

You are given infinite coins of denominations 5, 7, 9. Which of the following sum CANNOT be achieved using these coins? Correct Answer 13

One way to achieve a sum of 50 is to use ten coins of 5. A sum of 21 can be achieved by using three coins of 7. One way to achieve a sum of 23 is to use two coins of 7 and one coin of 9. A sum of 13 cannot be achieved.

Related Questions

The question below is followed by two statements I and II. You have to determine whether the data given is sufficient for answering the question. You should use the data and your knowledge of mathematics to choose the best possible answer.  Belly has some coins out of which some are of 25 Cent and Some are of 50 Cent. If he has a total of 250 coins, how many coins does he have of 25 Cent? I) Belly has three times as many as 50 Cent coins as 25 Cent coins. II) Belly has 20 more 25 cent coins than the 50 Cent coin.