Two identical pails L and M contained some water. Pail L was ¹₅ filled and Pail M was ¹₆ filled. The ratio of the total mass of Pail L and the water in it to the total mass of Pail M and the water in it was 8 : 7. The total mass of the two pails and the water they contained was 2700 g. What is the mass of an empty pail?
Mass of Pail L and the water inside = 8 u
Mass of Pail M and the water inside = 7 u

Total mass of the two pails and the water inside them
= 8 u + 7 u
= 15 u

15 u = 2700

1 u = 2700 ÷ 15 = 180

Mass of Pail L and the water in it more than mass of Pail M and the water in it 
= 8 u - 7 u
= 1 u

Fraction of the water that Pail L had more than Pail M 
= ¹₅ - ¹₆
= ⁶₃₀ - ⁵₃₀
= ¹₃₀ 

¹₃₀ of the water capacity → 1 u
⁵₃₀ of the water capacity → 5 x 1 u = 5 u

Mass of an empty pail
= 7 u - 5 u
= 2 u
= 2 x 180
= 360 g

Answer(s): 360 g