A. B two kinds of wine contain 75% and 55% alcohol respectively. Now we need to prepare 3000 grams of wine with 65% alcohol. How much should we take from each of the two kinds of wine?

A. B two kinds of wine contain 75% and 55% alcohol respectively. Now we need to prepare 3000 grams of wine with 65% alcohol. How much should we take from each of the two kinds of wine?

The first method: suppose 75% alcohol is x and 55% alcohol is y, then x + y = 3000, 0.75x + 0.55y = 0.65 × 3000, x = 1500 g, y = 1500 g. the second method: 75% alcohol = 3000 × (75% - 65%) / (75% - 55%) = 1500 g, 55% alcohol = 3000 ×

At present, there are some 60% and 40% alcohol, and 440G 45% alcohol should be prepared

Solution requires 60% alcohol x G
60%x+40%（440-x）=45%×440
60%x+176-40%x=198
20%x=22
x=110
40% alcohol: 440-110 = 330g

There are two kinds of alcohol with 85% and 45% concentration. Now we need to prepare 400 grams of alcohol with 60% alcohol. How many grams should we take from each of the two kinds of alcohol?

Let 85% be x g and 45% be (400-x) g
0.85x+0.45(400-x）=400×0.6
0.85x-0.45x=240-180
0.4x=60
x=150
400-150=250