<PRE><B>Question 394649</B>
(alcohol)/(fluid) = 25%
Let {{{a}}} = ounces of 20% solution needed
Let {{{b}}} = ounces of 35% solution needed
given:
(1) {{{a + b = 60}}} ounces
{{{.2a + .35b}}} alcohol in 25% solution
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(2) {{{(.2a + .35b)/60 = .25}}}
(2) {{{.2a + .35b = 15}}}
(2) {{{20a + 35b = 1500}}}
Multiply both sides of (1) by {{{20}}} and 
subtract (1) from (2)
(2) {{{20a + 35b = 1500}}}
(1) {{{-20a - 20b = -1200}}}
{{{15b = 300}}}
{{{b = 20}}}
{{{a = 60 - 20}}}
{{{a = 40}}}
40 ounces of 20% solution are needed
20 ounces of 35% solution are needed</PRE>