Question 1179771
Mixing  30% and 60% antifreezes
to make 90 gallons of 55% antifreeze


v gallons of the 60% antifreeze
{{{60v+30(90-v)=55*90}}}
-
{{{6v+3(90-v)=55*9}}}
{{{6v-3v+3*90=55*9}}}
{{{2v-v+90=55*3}}}
{{{v=55*3-90}}}
{{{highlight(v=75)}}}------gallons of the 60%
-
{{{highlight(15)}}}------gallons of the 30%