Question 725449
{{{x}}}= volume of water drained and replaced with antifreeze, in quarts
{{{x/(16-x)=1/2}}} is the ratio of antifreeze to water
{{{x/(16-x)=1/2}}} --> {{{2x=16-x}}} "equating the cross products", or multiplying both sides of the equal sign times {{{2(16-x)}}}
 
{{{2x=16-x}}} --> {{{2x+x=16-x+x}}} --> {{{3x=16}}} --> {{{x=16/3=5&1/3}}}
You need to drain {{{5&1/3}}} quarts of water and replace them with antifreeze.