Question 351479
Hi,
Let x be the total amount of the 70% alcohol solution.  then (72L -x) would be the total amount of the 34% alcoohol solution.
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question states:
.70*x + .34*(72L-x) = .47*72
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simplify and solve
.70*x + .34*72L- .34*x = .47*72L
.36*x = .47*72L - .34*72L
.36x = 9.36L
x = 26L  (the amount of the 70% alcohol solution needed to be used)