SOLUTION: How many quarts of pure antifreeze must be added to 2 quarts of a 10% antifreeze solution to obtain a 20% antifreeze solution?

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Question 1045066: How many quarts of pure antifreeze must be added to 2 quarts of a 10% antifreeze solution to obtain a 20% antifreeze solution?
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Using arithmetic with a variable,
let v be how much of the pure 100% antifreeze to add.
%282%2A10%2B100%2Av%29%2F%28v%2B2%29=20
Be sure this equation makes sense. When it does, then a large part of the problem has been handled. Solve for v.

%282%2Bv%2A10%29%2F%28v%2B2%29=2
10v%2B2=2%28v%2B2%29
10v%2B2=2v%2B4
8v=2
highlight%28v=1%2F4%29, which as quarts, would be 1 cup or 8 fluid ounces.