Two identical containers Q and R contained some water. Container Q was ¹₉ filled and Container R was ¹₁₀ filled. The ratio of the total mass of Container Q and the water in it to the total mass of Container R and the water in it was 15 : 14. The total mass of the two containers and the water they contained was 3480 g. What is the mass of an empty container?
Mass of Container Q and the water inside = 15 u
Mass of Container R and the water inside = 14 u

Total mass of the two containers and the water inside them
= 15 u + 14 u
= 29 u

29 u = 3480

1 u = 3480 ÷ 29 = 120

Mass of Container Q and the water in it more than mass of Container R and the water in it 
= 15 u - 14 u
= 1 u

Fraction of the water that Container Q had more than Container R 
= ¹₉ - ¹₁₀
= ¹⁰₉₀ - ⁹₉₀
= ¹₉₀ 

¹₉₀ of the water capacity → 1 u
⁹₉₀ of the water capacity → 9 x 1 u = 9 u

Mass of an empty container
= 14 u - 9 u
= 5 u
= 5 x 120
= 600 g

Answer(s): 600 g