Question 906813
a+b=12,
0.8*a+0.2*b=0.3*12
a=12-b
0.8*(12-b)+0.2*b=3.6
9.6-0.8b+0.2*b=3.6
-0.6*b=-6
b=10
a=12-b
a=2  liter at 80%
b=10  liter at 20%
check
0.8*2+0.2*10=0.3*12
1.6+2=3.6
3.6=3.6
ok