Level 3
A box is 400 g when it is 13 filled with stickers.
The same box is 700 g when it is 35 filled with stickers.
What is the mass of the empty box?
Level 2
Adam spends 14 of his money on some stickers.
He spends 13 of his remaining money on some marbles.
He spends a total of $200.
How much does Adam have at first?