The so-called butterfly crossing method is just a professional name that sounds good and is convenient for students to remember.

The steps are as follows:

(1) 3% and 8% and 5% respectively, both of which are larger values, and the smaller values are cut off to get 2% and 3% respectively;

The obtained values are 3% and 8% saline and 5% saline concentration difference, respectively.

(2) then crossing the two differences to take the ratio;

3% brine quality: 8% brine quality = 3% difference in ①: 2% difference in ① = 3: 2.

(3) Calculate the dosage of 3% and 8% brine in proportion.

The quality of brine is 1000×3÷(3+2)= 600g.

The mass of brine with 8% sum is 1000×2÷(3+2)=400 (g).

I wonder if I can understand the step-by-step answer for your reference.

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