<PRE><B>Question 236811</B>
    A chemist needs 160 milliliters of a 25% solution but has only 5% and 69% solutions available. Find how many milliliters of each that should be mixed to get the desired solution.
.
Let x = liters of 5% solution
then
160-x = liters of 69% solution
.
.05x + .69(160-x) = .25(160)
.05x +  110.4 - .69x = 15
110.4 - .64x = 15
-.64x = -95.4
x = 149.0625 milliliters (5% solution)
.
69% solution:
160-x = 160-149.0625 =  10.9375 milliliters (69% solution)
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