Accounts do not come out

Accounts do not come out

Three children enter a store to buy 3 bags of candy. each bag costs 5 euros and each of them paid with a 5 euros ticket. As they were good customers the shopkeeper made them a small
discount: returned 5 coins of 1 euro. The boys found that 5 euros are wrong to distribute between 3 so they stayed one for each and the remaining two gave them as a tip.

But when they left the store, they didn't get their accounts. Peter said:

Look, if each bag of candy worth 5 euros gives us one, it means that it cost us 4 euros each. therefore the three bags have cost 12 euros (4 x 3 = 12). Now, 12 euros plus 2 we have tipped add up to 14 (4 x 3 = 12 and 12 + 2 = 14).

What has been done of the missing euro until 15?

Can you help the three children discover this mystery?


Pedro, you're wrong, I already have it - says Jorge. The two euros we have tipped are not worth counting. Look, each bag has actually cost us 5 euros minus 1 that the shopkeeper returned:
4 x 3 = 12, so far good, but the ones that you have to add are the three euros that we have distributed, which are the ones that have reduced the price. Therefore, look closely: 4 x 3 = 12 and 12 + 3 = 15, which is the total money we were carrying.