Natalie was going to sell all of her stamp collection to buy a video game. After selling half of them she changed her mind. She then bought eleven more. How many did she start with if she now has 23?
So if she had 23 now I would say she started with 24:
So 23-11=12 so this was half of the stamps before buying the 11 extra
but 12x2=24 which would have been to total sum of stamps she started with.