1. One day, a young man came to Boss Wang's shop and bought a gift. The cost of this gift is 18 yuan, and the list price is 2 1 yuan. The young man took out 100 yuan to buy this gift. Boss Wang didn't have any change at that time, so he changed 100 yuan from the neighborhood and gave it to the young man 79 yuan. But later, the neighborhood found that this 100 yuan was counterfeit, and Boss Wang had no choice but to return this 100 yuan to the neighborhood. Excuse me: How much did Boss Wang finally lose in this transaction?

There are six pigs crossing the river, including three teams of mothers and children. The first team of mothers and children can row boats; The second team of mothers will, but the children will not; The mother of the third team can do it, but the children can't. There is a boat that can only carry two pigs at a time. Mother pig should protect her children, or other sows will eat their children. All six pigs must cross the river safely. What should we do?

One of the 26 ping-pong balls is defective. The appearance of defective products is exactly the same as that of genuine products, but slightly lighter than the specified weight. How many times should I at least weigh the defective products on the scale now?

4. Fill in+,-,×, e in "?"in () Fill in the numbers, and the results of the three formulas are the same. How to fill it out?

6( )8( )3( )2( )7=?

7( )3( )5( )4( )2=?

9( )4( )3( )6( ) 1=?

5. Three people went to a hotel and stayed in three rooms, each room was 10 yuan, so they gave the boss 30 yuan money. The next day, the boss said that there were enough rooms in 25 yuan and asked my brother to return them to three guests, 5 yuan. Who knows, my brother was greedy, only gave everyone a refund of 1 yuan, and secretly took 2 yuan himself. This is equivalent to three guests each spent nine dollars, so three people spent a * * * 27 dollars, plus the little brother took two dollars, a total of * * * 29 dollars. But at the beginning, all three of them gave their lives 30 yuan. What about 1 yuan?

6. Two rings with radii of 1 and 2 respectively. The small circle revolves around the circle of the big circle in the big circle. How many times did the small circle turn? If you go around the outside of the big circle, how many times does the small circle turn?

7, 1 yuan a bottle of soda, drink two empty bottles for one bottle of soda. If you spend 20 yuan money, how many bottles of soda can you drink?

8. A manager has three daughters. The sum of the ages of the three daughters is equal to 13, and the age of the three daughters is equal to the age of the manager. A subordinate knows the manager's age, but still can't determine the age of the manager's three daughters. The manager said that only one daughter's hair was black, and this subordinate got the ages of the manager's three daughters on this basis. How old are the manager's three daughters? Why?

9. In a competition, Xiaodong scored 197 in Chinese and science, 199 in Chinese and mathematics, and 196 in mathematics and science. What subjects did Xiaodong take? How is Xiaodong's performance in all subjects?

10, a piece of cake, cut three times, cut into eight parts on average (each part is the same), how to cut it?