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A chemist needs a 30% iron alloy. How many grams of a 70% iron alloy must be mixed with 16 grams of a 20% iron alloy to obtain the requiered 30% alloy?

Respuesta :

Let x=grams of 70% alloy:
0.70x+16×0.20=0.30(x+16)
0.70x=0.30x+4.8-3.2
0.40x=1.6
x=1.6/0.4=16/4=4g
4 grams of 70% alloy are needed.