Question 365378
Let x be the amount of 24% solution, y the amount of 50% solution.
1.{{{x+y=100}}}
 .
.
.
{{{24x+50y=36(100)}}}
2.{{{12x+25y=1800}}}
Multiply eq. 1 by -12 and add to eq. 2,
{{{-12x-12y+12x+25y=-1200+1800}}}
{{{13y=600}}}
{{{highlight(y=600/13)}}}gallons
Then from eq. 1,
{{{x+600/13=100}}}
{{{highlight(x=700/13)}}}gallons