The analysis is as follows:
The first process: If this 50 yuan is real money, then the shoe store owner has made a net profit 10 yuan. Because the purchase price was 20 yuan, it was sold to 30 yuan, with the gross profit 10 yuan.
The second process: Now it is found that this 50 yuan is fake money, and the shoe store owner lost 50 yuan after earning 10 yuan, which is equivalent to losing 40 yuan.
40 yuan's answer is only in the field of mathematics. Simple addition and subtraction calculation in business is wrong.
In business, it is calculated as follows:
The first process: If this 50 yuan is real money, then the shoe store owner has made a net profit 10 yuan. Because the purchase price was 20 yuan, it was sold to 30 yuan, with the gross profit 10 yuan.
That is to say, the total wealth of shoe store owners has increased by 10 yuan, and the total amount is: the wealth of shoe store owners+10 yuan.
The second process: Now it is found that this 50 yuan is fake money, then the shoe store owner lost 50 yuan, and the total amount is: Shoe store owner wealth -50 yuan.
The difference between the two is that:
Shoe store owner wealth+10 yuan minus shoe store owner wealth -50 yuan =60 yuan.
For example, the boss's original total assets were 1000 yuan. If it is not fake money, his wealth should be 10 10 yuan. After discovering fake money, wealth became 950 yuan. Before and after the difference in 60 yuan, that is, the fake money incident, reduced its property 60 yuan.