Answer
20 liters of the 10% solution and 30 liters of the 60% solution
Work Step by Step
10% and 60% solution
50 liters needed
Let $x$ and $y$ be the amounts of the 10% and 60% solutions used, respectively.
$x+y=50$
$.1x+.6y=50*.4$
$.1x+.6y=20$
$x+y=50$
$x+y-y=50-y$
$x=50-y$
$.1x+.6y=20$
$.1(50-y)+.6y=20$
$.1*50-y*.1+.6y=20$
$5-.1y+.6y=20$
$5+.5y=20$
$5+.5y-5=20-5$
$.5y=15$
$.5y*2=15*2$
$y=30$
$x+y=50$
$x+30=50$
$x+30-30=50-30$
$x=20$