Let x be the mass of oil in the first vessel. Then the second vessel has (5/7)x, and the third vessel has (3/4)*(5/7)x = (15/28)x. The total is x + (5/7)x + (15/28)x = 32. Multiplying by 28: 28x + 20x + 15x = 896. 63x = 896. x = 896/63 ≈ 14.22 L. Second vessel: (5/7)*14.22 ≈ 10.16 L. Third vessel: (15/28)*14.22 ≈ 7.61 L.