Answer:
10 liters of pure alcohol
Step-by-step explanation:
Create an equation where x is the number of liters of pure alcohol needed:
1x + (0.4)(20) = (20 + x)(0.6)
Simplify:
x + 8 = 0.6x + 12
Solve for x:
0.4x = 4
x = 10
So, 10 liters of pure alcohol have to be added
