Question 346060
Let {{{A}}} be the amount of pure antifreeze and {{{B}}} the amount of 40% solution.
Total amount equation:
1.{{{A+B=12}}}
Concentration equation:
{{{100A+40B=50(12)}}}
{{{100A+40B=600}}}
2.{{{5A+2B=30}}}
Multiply eq. 1 by (-2) and add to eq. 2,
{{{-2A-2B+5A+2B=-24+30}}}
{{{3A=6}}}
{{{highlight(A=2)}}}quarts
Then from eq. 1,
{{{2+B=12}}}
{{{highlight(B=10)}}}quarts