1, a factory has a batch of coal, originally planned to burn 0.25 tons per day, which can burn 100 days; In fact, burning coal every day is 20% less than originally planned. How many days can it actually burn? (Answer in proportion)

Actual: 0.25x( 1-20%)=0.2 (ton)

Solution: Suppose it can actually burn for x days.

0.25:0.2=x: 100

x= 125

2. It takes Party A 6 minutes and Party B 4.5 minutes to manufacture a part. Now there are 2 100 parts assigned to them, which are required to be completed at the same time. How much should each person allocate? (It is best to solve it by proportional method)

The speed ratio of Party A and Party B: 1/6: 1/4.5 = 3: 4.

Each copy: 2 100/(3+4)=300 (pieces)

A: 300x3=900 (pieces)

B: 300x4= 1200 (unit)

3. Warehouse A and Warehouse B each have 1 1,680 tons. If 1 is taken from Warehouse A and put into Warehouse B, the mass ratio of white sugar in Warehouse A and Warehouse B is 4: 3. How many tons of sugar are there in warehouse A and warehouse B?

After the performance:

Each serving: 1680/(4+3)=240 (ton)

Answer: 240x4=960 (ton)

B: 240x3=720 (ton)

The result shows that A is 960/(1-1/5) =1200 (ton).

It turns out that B has: 1680- 1200=480 (tons).