SOLUTION: A jeweler has five rings, each weighing 18grams, made of an alloy of 10% silver and 90% gold. He decides to melt down the rings and add enough silver to reduce the gold content to

Algebra ->  Distributive-associative-commutative-properties -> SOLUTION: A jeweler has five rings, each weighing 18grams, made of an alloy of 10% silver and 90% gold. He decides to melt down the rings and add enough silver to reduce the gold content to       Log On


   

Question 1133067: A jeweler has five rings, each weighing 18grams, made of an alloy of 10% silver and 90% gold. He decides to melt down the rings and add enough silver to reduce the gold content to 60%. How much silver should he add?
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
90 grams total with 9gm (10%) pure silver and 81gm (90%) pure gold. After adding more silver, it will be 40%
so (9+x)/(90+x)=2/5, which is 40%
cross-multiply
5(9+x)+2(90+x)
45+5x=180+2x
3x=135
x=45gm silver ANSWER
the total amount of metal will be 135 gm, and now 54 of that (9+45) will be silver.
therefore, 81gm of the 135 will be gold and that is 60%.