Answer: There are a lot of examples of this, but in short, any number that can be written as 1/2 is your answer. Think about it, 5 is half of 10. So that means that 20/40, 6/12, 3/6, 70/140, etc are all equal
Think of it this way: your friend is thinking of a year, and you have to guess which. She has told you the year is in the 20th century (1900s). There are 100 years in the 20th century (1901-1999 plus 1900). There can be 100 possibilities
