It was a Sunday morning. Peter, a seven-year-old boy, watched TV in the room while his brother Bill did his homework. Their father watered the flowers in the garden and their mother went out to do some shopping. At ten the woman came back with a heavy basket. Peter ran up to her. He wanted to know what his mother bought. He found a bag of oranges in it. He liked them very much and wanted to eat. His mother stopped him. She gave five to each son and went to cook food. Peter ate his oranges soon but his brother was busy doing his homework and didn't eat his. Suddenly the telephone rang and Bill ran to answer it. Bill's friend asked him to play football with them. And when Bill talked with his friend, Peter took two of his oranges away and ate them. Bill found it and called him out and beat  him behind the house. Peter didn't tell his parents about it. The next morning Peter's teacher, Mrs Ball, taught the students subtraction . Peter didn't listen to her carefully and couldn't understand it. So he couldn't answer her questions. The teacher began to give him an example, "If your brother has five oranges and you take two from him, what will the result be?" "He'll beat me, madam," answered the boy. All his classmates began to laugh. When did Peter's mother come back?
At five. At six. At seven. At ten.