A chemist has three different acid solutions. The first acid solution contains 20 % 20% acid, the second contains 30 % 30% and the third contains 60 % 60% . They want to use all three solutions to obtain a mixture of 90 90 liters containing 35 % 35% acid, using 2 2 times as much of the 60 % 60% solution as the 30 % 30% solution. How many liters of each solution should be used