Maria doesn’t like to tell people her real age. When somebody asks her how old she is, she says that she is twenty-one. (Maria mentally omits all Sundays because on Sundays she doesn’t work, so she claims she doesn’t get any older.)
How old is Maria really?
Answer
Maria could be either 24 or 25. She subtracted one-seventh of her real age.
If she were actually 24.5 years old, she could claim that she was 21 (24.5 * 6/7 = 21).
If she were actually 25.6 years old, she could also claim that she was 21 (25.6 * 6/7 = 21.9 (rounded).
