SOLUTION: What quantity of 20% acid solution must be mixed with 360 mL of 90% acid solution to produce 40% acid solution?

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Question 1010109: What quantity of 20% acid solution must be mixed with 360 mL of 90% acid solution to produce 40% acid solution?
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
x ml 0.20 acid
360 ml 0.90 acid
they equal (360+x)0.40 acid
0.2x+324=144_0.40x
-0.2x=-180
x=900 ml of 20% acid
This should be a 5/2 ratio, since 40% is 2/5 of the way from 20% to 90%
900 is 5/2 360.