Ask for the original amount of alcohol in the pot, and tell the change and final result of the wine in the pot-multiply it by three (multiply it by two) and then subtract it quantitatively (lose weight). To solve this problem, it is generally based on the changed results, using the reciprocal relationship of multiplication and division, addition and subtraction, and gradually reverse reduction. "When you meet three flowers in a shop, you will drink all the wine in the pot." As you can see, when you meet three flowers, there will be a bar bucket in the pot, a bar bucket of 1÷2 when you meet three flowers, and a bar bucket of 1÷2+ 1 when you meet two flowers.

[( 1÷2+ 1)÷2+ 1]

2=7/8 (barrel)

So, the pot hit 7/8.

The key point of the above solution lies in inverse reduction, which can also be expressed by schematic diagram or line segment diagram.

Of course, if we use algebra to solve this problem, the quantitative relationship will be more clear. There are x barrels of wine in the pot. List the equations according to the meaning of the question.

2[2(2x- 1)- 1]

- 1=0

X=7/8 (barrel) is obtained by solving.