Question 356697
{{{0.40x + 0.65(20-x) = 20*0.50}}},
{{{0.40x + 13-0.65x = 10}}},
{{{-0.25x = -3}}},
{{{x = 12}}}, # liters 40% alcohol solution, and 20 - 12 = 8 liters 65% alcohol solution.