Two identical tanks H and J contained some water. Tank H was ¹₉ filled and Tank J was ¹₁₀ filled. The ratio of the total mass of Tank H and the water in it to the total mass of Tank J and the water in it was 15 : 14. The total mass of the two tanks and the water they contained was 6380 g. What is the mass of an empty tank?
Mass of Tank H and the water inside = 15 u
Mass of Tank J and the water inside = 14 u

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

29 u = 6380

1 u = 6380 ÷ 29 = 220

Mass of Tank H and the water in it more than mass of Tank J and the water in it 
= 15 u - 14 u
= 1 u

Fraction of the water that Tank H had more than Tank J 
= 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 tank
= 14 u - 9 u
= 5 u
= 5 x 220
= 1100 g

Answer(s): 1100 g