how much pure alcohol should be added to 20 liters of 40% alcohol to increase the concentration to 50% alcohol

Answer 1

x + (0.20)(40) = (0.50)(40 + x)

Can you solve for x and answer?

Answer 2

x + (0.20)(40) = (0.50)(40 + x)

calculates to 6 more liters of pure alcohol

14/26>.5 so something is wrong with

previous answer.

the equation should be

.4*20+x amount pure alcohol after x added

equals

.5*(20+x) ,,,, 20 plus amount at 50% alcohol

8+x=10+x/2

x = 4 and it checks out since (8+4)/24=.5