Two identical tanks V and W contained some water. Tank V was ¹₆ filled and Tank W was ¹₇ filled. The ratio of the total mass of Tank V and the water in it to the total mass of Tank W and the water in it was 10 : 9. The total mass of the two tanks and the water they contained was 2660 g. What is the mass of an empty tank?
Mass of Tank V and the water inside = 10 u
Mass of Tank W and the water inside = 9 u

Total mass of the two tanks and the water inside them
= 10 u + 9 u
= 19 u

19 u = 2660

1 u = 2660 ÷ 19 = 140

Mass of Tank V and the water in it more than mass of Tank W and the water in it 
= 10 u - 9 u
= 1 u

Fraction of the water that Tank V had more than Tank W 
= 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 tank
= 9 u - 6 u
= 3 u
= 3 x 140
= 420 g

Answer(s): 420 g