## Algebra and Trigonometry 10th Edition

$x=12; y=18$
Let $x$ and $y$ be the number of liters in the $25 \%$ solution and $50 \%$ solution, respectively. The system of two equations is: $x+y=30 \\ 0.25 x+0.5 y=12$ Multiply the first equation by $-5$ and then add the new equation to equation $2$. $-0.5x-0.5y+0.25x+0.5 y=-15+12$ The yields $x=12$ Substitute the value of $x$ into the first equation to get the value of $y$. $12+y=30 \implies y=18$ Thus, $x=12; y=18$