SOLUTION: How much 15% acid must you add to 4 liters of 40% acid to obtain a mixture that is 25% acid?

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Question 198989: How much 15% acid must you add to 4 liters of 40% acid to obtain a mixture that is 25% acid?
Answer by RAY100(1637) About Me  (Show Source):
You can put this solution on YOUR website!
Let x = amt of acid
.
.4(4) + .15x = .25(4+x)
.
1.6 + .15 x = 1 + .25x
.
.6 = .1x
.
x= 6 liters
.
check
.
.4(4) + .15(6) = .25(4 + 6)
1.6 + .9 = 2.5 ,,,,,ok