SOLUTION: Sam is a jewellery artist. She needs to mix metals to make her products. Pure gold is 24-karat and is very soft. It is usually mixed with other metals such as silver to make it har

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: Sam is a jewellery artist. She needs to mix metals to make her products. Pure gold is 24-karat and is very soft. It is usually mixed with other metals such as silver to make it har      Log On


   

Question 1145206: Sam is a jewellery artist. She needs to mix metals to make her products. Pure gold is 24-karat and is very soft. It is usually mixed with other metals such as silver to make it harder. Sam has some 18-karat gold(18over24) and some 9-karat gold(9over24 pure gold). What mass of each type of gold should she use to make 600g of 15-karat gold?
Answer by josgarithmetic(39623) About Me  (Show Source):
You can put this solution on YOUR website!
Note that 18 karat is twice the concentration of 9 karat.

w grams of the 18 karat gold
600-w grams of the 9 karat gold

18w%2B9%28600-w%29=15%2A600
2w%2B600-w=5%2A200
w=1000-600
highlight%28w=400%29---------grams of the 18 karat gold
200---------------grams of the 9 karat gold