Answer: Let's start by assuming that Matilde started out with some amount of money, which we will call "x" (in euros).
According to the problem, she spent two-thirds of her money in the first shop. This means that she had one-third of her money left after leaving the first shop:
Money left after first shop = x - (2/3)x = (1/3)x
Matilde then spent two-thirds of this remaining money in the second shop. This means that she had one-third of her original money left after leaving the second shop:
Money left after second shop = (1/3)x - (2/3)(1/3)x = (1/9)x
We are told that she had €18 left at this point so that we can set up an equation:
Money left after second shop = (1/9)x = 18
Solving for x, we get:
x = 162
Therefore, Matilde started out with €162.
Explanation: