To support Sichuan earthquake relief, the cross will transport 160 tons of relief goods to the disaster area In order to support the earthquake relief in Sichuan, the cross society has to transport 160 tons of relief goods to the disaster area for no more than 12 days. There are two kinds of cars to rent, the freight of type A is 30 yuan per ton, and that of type B is 25 yuan per ton. The transportation capacity is 16 tons per day for type A and 12 tons per day for type B, but only one kind of car can be rented every day. Due to the long distance, no car runs once a day There are three kinds of renting schemes: 1. Renting only type A; 2. Renting only type B; 3. Renting type A for a period of time, then forming type B for a period of time, just 12 days to complete If you are the person in charge of the cross society, which one will you choose (considering the freight) and explain the reason

To support Sichuan earthquake relief, the cross will transport 160 tons of relief goods to the disaster area In order to support the earthquake relief in Sichuan, the cross society has to transport 160 tons of relief goods to the disaster area for no more than 12 days. There are two kinds of cars to rent, the freight of type A is 30 yuan per ton, and that of type B is 25 yuan per ton. The transportation capacity is 16 tons per day for type A and 12 tons per day for type B, but only one kind of car can be rented every day. Due to the long distance, no car runs once a day There are three kinds of renting schemes: 1. Renting only type A; 2. Renting only type B; 3. Renting type A for a period of time, then forming type B for a period of time, just 12 days to complete If you are the person in charge of the cross society, which one will you choose (considering the freight) and explain the reason

From the point of view of saving freight and arriving on time, we should mainly use B-type cars, and use A-type cars to adjust the shortage
(160-12 * 12) / (16-12) = 4 days (4 days for type a vehicles)
12-4 = 8 days (8 days for vehicle type b)
The total freight is 8 * 12 * 25 + 4 * 16 * 30 = 4320 yuan

2. A batch of goods will be transported by several vehicles, each vehicle will carry 3.5 tons of goods, and 2 tons of these goods can not be transported away; if each vehicle carries 4 tons of goods, then

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Several vehicles are used to ship a batch of goods. If each vehicle carries 3.5 tons of goods, then 2 tons of the goods can not be transported away. If each vehicle carries 4 tons of goods, then after loading this batch of goods, 1 ton of other goods can be loaded. Question: how many vehicles are there? How many tons of the goods are there?

Set X cars, y tons of goods
3.5x+2=y
4x-1=y
The solution is x = 6
y=23