A chemist has three different acid solutions. The first acid solution contains 15% acid, the second contains 35% and the third contains 55%. They want to use all three solutions to obtain a mixture of 280 liters containing 25% acid, using 3 times as much of the 55% solution as the 35% solution. How many liters of each solution should be used? The chemist should use and liters of 15% solution, 7 liters of 35% solution, liters of 55% solution.