Two identical containers M and N contained some water. Container M was ¹₂ filled and Container N was ¹₃ filled. The ratio of the total mass of Container M and the water in it to the total mass of Container N and the water in it was 6 : 5. The total mass of the two containers and the water they contained was 1210 g. What is the mass of an empty container?
Mass of Container M and the water inside = 6 u
Mass of Container N and the water inside = 5 u

Total mass of the two containers and the water inside them
= 6 u + 5 u
= 11 u

11 u = 1210

1 u = 1210 ÷ 11 = 110

Mass of Container M and the water in it more than mass of Container N and the water in it 
= 6 u - 5 u
= 1 u

Fraction of the water that Container M had more than Container N 
= ¹₂ - ¹₃
= ³₆ - ²₆
= ¹₆ 

¹₆ of the water capacity → 1 u
²₆ of the water capacity → 2 x 1 u = 2 u

Mass of an empty container
= 5 u - 2 u
= 3 u
= 3 x 110
= 330 g

Answer(s): 330 g