Two identical containers A and B contained some water. Container A was ¹₇ filled and Container B was ¹₈ filled. The ratio of the total mass of Container A and the water in it to the total mass of Container B and the water in it was 12 : 11. The total mass of the two containers and the water they contained was 5060 g. What is the mass of an empty container?
Mass of Container A and the water inside = 12 u
Mass of Container B and the water inside = 11 u

Total mass of the two containers and the water inside them
= 12 u + 11 u
= 23 u

23 u = 5060

1 u = 5060 ÷ 23 = 220

Mass of Container A and the water in it more than mass of Container B and the water in it 
= 12 u - 11 u
= 1 u

Fraction of the water that Container A had more than Container B 
= ¹₇ - ¹₈
= ⁸₅₆ - ⁷₅₆
= ¹₅₆ 

¹₅₆ of the water capacity → 1 u
⁷₅₆ of the water capacity → 7 x 1 u = 7 u

Mass of an empty container
= 11 u - 7 u
= 4 u
= 4 x 220
= 880 g

Answer(s): 880 g