Level 2
Adam has 500 stickers.
After giving some stickers to his students,
he has 100 stickers left.
Each student receives 10 stickers.
How many students does he give to?
Level 3
There are 3 boxes.
The total mass of Box A and Box B is 160 kg.
The total mass of Box B and Box C is 200 kg.
The total mass of Box C and Box A is 180 kg.
Find the total mass of Box A, Box B and Box C.