Old cobbler Karl made boots and sent his son Hans to the market to sell them for 25 talers. At the market, two disabled men (one without a left leg, the other without a right leg) approached the boy and asked him to sell them each a boot. Hans agreed and sold each boot for 12.5 talers.

When the boy came home and told his father everything, Karl decided that the disabled men should have been sold the boots cheaper - each for 10 talers. He gave Hans 5 talers and told him to return 2.5 talers to each disabled man.

While the boy was looking for the disabled men at the market, he saw that sweets were being sold, couldn't resist, and spent 3 talers on candies. After that, he found the disabled men and gave them the remaining money - one taler each. Returning home, Hans realized how badly he had acted. He told everything to his father and asked for forgiveness. The cobbler got very angry and punished his son by putting him in a dark storeroom.

Sitting in the storeroom, Hans thought about it. It turned out that since he had returned one taler to each, the disabled men had paid 11.5 talers for each boot:

$12.5-1=11.5$. So, the boots cost 23 talers: $2 \cdot 11.5=23$. And Hans had spent 3 talers on candies, so in total it comes to 26 talers:

$23+3=26$. But there were only 25 talers! Where did the extra taler come from?
Think about how much money Karl should have received, how much he actually received, and why.

## Solution

The disabled people paid 23 talers for the boots, but Karl received only 20, as Hans spent the remaining 3 talers on candies. Sitting in the pantry, Hans added the income (23 talers) to the expense (3 talers). This sum makes no sense. If he had calculated the difference between income and expense, the "net" income would have been the 20 talers that Karl ultimately received.