SOLUTION: A jeweler has 3 rings, each weighing 15 g, made of an alloy of 25 percent silver and 75 percent gold. He decides to melt down the rings and add enough silver to reduce the gold con

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Question 812764: A jeweler has 3 rings, each weighing 15 g, made of an alloy of 25 percent silver and 75 percent gold. He decides to melt down the rings and add enough silver to reduce the gold content to 65 percent. How much silver should he add?
a) Write an equation for the total amount of gold in the mixture. Use s to represent the amount of silver added.
b) Solve this equation for s. Include the appropriate units in your answer.
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Focus on concentration of Gold (but this is arbitrary).
Let g = grams of Silver to add.

15%2A75%2F%2815%2Bg%29=65

If you could read and analyze the description and obtain that equation, or an equivalent one, then you have solved most of the problem. The rest is only a few arithmetic steps.

15%2A15%2F%2815%2Bg%29=13
15%2A15=13%28g%2B15%29
15%2A15=13g%2B13%2A15
15%2815-13%29=13g
30=13g
highlight%28g=30%2F13=2%264%2F13%29 grams of silver