One, everyone paid 100 yuan, three people were 300 yuan, and then returned to 50 yuan. As a result, the waiter took it to 20 yuan, that is, everyone took 10 yuan, and everyone took 90 yuan's room rate, ***270 yuan, but the thing was 250 yuan's room rate, and as a result, 20 yuan was spent more, which was taken away by the waiter. The problem itself deliberately added 20 yuan to 270 yuan, but the thing is that the room rate of 270 yuan should be deducted from 20 yuan. Second, measure 4 liters for Xiaoli from the 4-liter bottle (don't put it into the 5-liter bottle yet), and then measure 4 liters into the 5-liter bottle, so that the 5-liter bottle is 1 full. Now put a 4-liter bottle into a 5-liter bottle. The 5-liter bottle is full, 4 liters are just poured out 1 liter, and the remaining 3 liters are given to Xiaohua. The first four liters belong to Xiao Li. 3. The results in absolute values are all negative, so if the absolute values are removed, | 1/2- 1 | should become1-1/2; | 1/3- 1/2 | should be changed to 1/2- 1/3 ... The absolute value of the result is: 1- 1/2-65438. 1- 1/ 100 = 99/ 100.