SOLUTION: How much pure gold (24K) must be mixed with 70% gold to get 30 grams (g) of 80% gold? Express in decimal form rounded to one decimal place.

Question 1157076: How much pure gold (24K) must be mixed with 70% gold to get 30 grams (g) of 80% gold? Express in decimal form rounded to one decimal place.
Found 2 solutions by josgarithmetic, MathTherapy:
Answer by josgarithmetic(39617) (Show Source): You can put this solution on YOUR website!
g of 100%
30-g of 70%

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Answer by MathTherapy(10552) (Show Source): You can put this solution on YOUR website!

How much pure gold (24K) must be mixed with 70% gold to get 30 grams (g) of 80% gold? Express in decimal form rounded to one decimal place.

Let amount of pure gold be G
Then amount of 70% gold = 30 - G
We then get: G + .7(30 - G) = .8(30)
G + 21 - .7G = 24
G - .7G = 24 - 21
.3G = 3
Amount of pure gold, or
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