From the autumn of 2009 to May of this year, there was a serious drought in our city. From April 15 to 21 this year, both a and B middle schools had no water supply. The higher authorities immediately organized water supply activities, and each time they sent 7600 liters to a middle school and 4000 liters to B middle school. It is known that the per capita water supply is the same, the number of teachers and students in a middle school is two times that of B middle school, 20 less. (1) how many teachers and students are there in these two middle schools? (2) If you send bottled water, the price is 1 yuan / L; if you send drinking spring water by fire truck, you don't need to buy it, but you need to deliver water tower. The price of 500 liter water tower is 520 yuan / piece. Other expenses are ignored. Please calculate the cost of sending all bottled water or all drinking spring water by fire truck for the first time?

From the autumn of 2009 to May of this year, there was a serious drought in our city. From April 15 to 21 this year, both a and B middle schools had no water supply. The higher authorities immediately organized water supply activities, and each time they sent 7600 liters to a middle school and 4000 liters to B middle school. It is known that the per capita water supply is the same, the number of teachers and students in a middle school is two times that of B middle school, 20 less. (1) how many teachers and students are there in these two middle schools? (2) If you send bottled water, the price is 1 yuan / L; if you send drinking spring water by fire truck, you don't need to buy it, but you need to deliver water tower. The price of 500 liter water tower is 520 yuan / piece. Other expenses are ignored. Please calculate the cost of sending all bottled water or all drinking spring water by fire truck for the first time?

(1) Suppose that there are x teachers and students in secondary school B, then there are (2x-20) teachers and students in secondary school A. according to the meaning of the question, we get 76002x − 20 = 40000x. Solving this equation, we get x = 200. After the test, x = 200 is the solution of the original equation, ｜ 2x-20 = 380. A: there are 380 teachers and students in secondary school a and 200 teachers and students in secondary school B. (2) the cost of delivering bottled water is 4000 × 1 = 4000 (yuan), and the cost of delivering drinking spring water is 4000500 × 520 = 4160（ Yuan)