Alien Money
Below are coins in an alien currency, Pikolines.
A, B, and C represent the same amount of money.
If the triangles are worth 10 Pikolines, how much are the round and square coins worth?
The round coins are worth 30 Pikolines, and the square ones 20 Pikolines.
If you compare A and C, you can see that one circular coin is worth three triangular coins.
Comparing A and B shows that adding a square coin and a triangular one results in a circular coin.