Two identical tanks X and Y contained some water. Tank X was ¹₉ filled and Tank Y was ¹₁₀ filled. The ratio of the total mass of Tank X and the water in it to the total mass of Tank Y and the water in it was 14 : 13. The total mass of the two tanks and the water they contained was 2970 g. What is the mass of an empty tank?
Mass of Tank X and the water inside = 14 u
Mass of Tank Y and the water inside = 13 u

Total mass of the two tanks and the water inside them
= 14 u + 13 u
= 27 u

27 u = 2970

1 u = 2970 ÷ 27 = 110

Mass of Tank X and the water in it more than mass of Tank Y and the water in it 
= 14 u - 13 u
= 1 u

Fraction of the water that Tank X had more than Tank Y 
= 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
= 13 u - 9 u
= 4 u
= 4 x 110
= 440 g

Answer(s): 440 g