Two identical pails D and E contained some water. Pail D was ¹₃ filled and Pail E was ¹₄ filled. The ratio of the total mass of Pail D and the water in it to the total mass of Pail E and the water in it was 6 : 5. The total mass of the two pails and the water they contained was 2420 g. What is the mass of an empty pail?
Mass of Pail D and the water inside = 6 u
Mass of Pail E and the water inside = 5 u

Total mass of the two pails and the water inside them
= 6 u + 5 u
= 11 u

11 u = 2420

1 u = 2420 ÷ 11 = 220

Mass of Pail D and the water in it more than mass of Pail E and the water in it 
= 6 u - 5 u
= 1 u

Fraction of the water that Pail D had more than Pail E 
= ¹₃ - ¹₄
= ⁴₁₂ - ³₁₂
= ¹₁₂ 

¹₁₂ of the water capacity → 1 u
³₁₂ of the water capacity → 3 x 1 u = 3 u

Mass of an empty pail
= 5 u - 3 u
= 2 u
= 2 x 220
= 440 g

Answer(s): 440 g