SOLUTION: A pot contains 8 L of brine at a concentration of 70 g/L. How much of the water should be boiled off to increase the concentration to 200 g/L?

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Question 784430: A pot contains 8 L of brine at a concentration of 70 g/L. How much of the water should be boiled off to increase the concentration to 200 g/L?
Answer by josgarithmetic(39620) About Me  (Show Source):
You can put this solution on YOUR website!
Initially, 8%2A70%2F%288%29=70 g/L

Boil off v liters of water to increase concentration:
8%2A70%2F%288-v%29=200 and solve for v.
'
8%2A70=%288-v%29200
8-v=8%2A70%2F200
8-8%2A70%2F200=v
v=8%281-7%2F20%29=8%2820-7%29%2F20=8%2A13%2F20=2%2A13%2F5=26%2F5
v=5%261%2F5+Liters