Coins and a cranky pnome #1

Late one summer the Swansong family moved into their new home - a large cave dug into the base of an ancient oak tree. The cave had a spooky history. It was said to be haunted by a cranky old pnome who did not like unsolved problems.

There were two children in the pnome family, Jonsim who was 9 years old and Mara who was 11 years old. That night, they settled into their comfortable beds and were soon asleep. Then Jonsim began to dream.

The cranky pnome whispered to him in his dream, "I have two problems that have been keeping me awake for a long long time. I want to rest and not haunt this cave anymore. But I can’t rest until both problems are solved. Jonsim, solve this problem for me as quickly as you can. You have nine coins: 3 quarters, 3 dimes, and 3 nickels. Place one coin in each of nine boxes so that the sum of the coins in each line of three boxes is 40 cents."

Jonsim woke in a sweat. Lying beside his pillow were nine coins and a piece of paper on which were drawn nine boxes joined by lines.

He began working on the problem. The cranky pnome needed his help.