Two identical containers C and D contained some water. Container C was ¹₆ filled and Container D was ¹₇ filled. The ratio of the total mass of Container C and the water in it to the total mass of Container D and the water in it was 9 : 8. The total mass of the two containers and the water they contained was 1700 g. What is the mass of an empty container?
Mass of Container C and the water inside = 9 u
Mass of Container D and the water inside = 8 u

Total mass of the two containers and the water inside them
= 9 u + 8 u
= 17 u

17 u = 1700

1 u = 1700 ÷ 17 = 100

Mass of Container C and the water in it more than mass of Container D and the water in it 
= 9 u - 8 u
= 1 u

Fraction of the water that Container C had more than Container D 
= ¹₆ - ¹₇
= ⁷₄₂ - ⁶₄₂
= ¹₄₂ 

¹₄₂ of the water capacity → 1 u
⁶₄₂ of the water capacity → 6 x 1 u = 6 u

Mass of an empty container
= 8 u - 6 u
= 2 u
= 2 x 100
= 200 g

Answer(s): 200 g