Corner Store

Akpos stopped by the corner provision store and read the following list to the shop attendant:

10 pounds sugar at N1.25 per gram
4 pounds coffee at N1.50 per gram
2 pounds butter at N1.10 per gram
2 bars soap at N.83 each

"How much does that come to?" asked Akpos.

"Twenty-two naira and thirty-six kobo."

"If I gave you three ten naira bills, how much change would I get?" asked the boy.

"Seven naira and sixty-four kobo," stated the shop attendant who appeared to be irritated by all the questions.

Akpos said, as he disappeared through the door, "Sorry I don't want to buy the items... that's our mathematics lesson for tomorrow, and I needed some help with it."