A chemist has three different acid solutions. The first acid solution contains 20 % acid, the second contains 30 % and the third contains 60 % . He wants to use all three solutions to obtain a mixture of 54 liters containing 45 % acid, using 2 times as much of the 60 % solution as the 30 % solution. How many liters of each solution should be used? The chemist should use liters of 20 % solution, liters of 30 % solution, and liters of 60 % solution.