Math Problem Solving

Young Larry stopped by the corner grocery store and read the following list to the clerk:

10 pounds sugar at $1.25 a pound
4 pounds coffee at $1.50 a pound
2 pounds butter at $1.10 a pound
2 bars soap at $.83 each

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

"Twenty-two dollars and thirty-six cents."

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

"Seven dollars and sixty-four cents," stated the clerk who appeared to be irritated by all the questions.

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