Box A and Box B are identical. ⁵₆ of Box A and ⁵₈ of Box B are filled with sand. The mass of Box B with its contents is ⁸₉ the mass of Box A with its contents. The total mass of the two boxes with their contents is 595 kg. Find the mass of an empty box.
Mass of Box A and its contents = 9 u
Mass of Box B and its contents = 8 u

Total mass of the two boxes with their contents
= 9 u + 8 u
= 17 u

17 u = 595 

1 u = 595 ÷ 17 = 35

Mass of Box A with its concents more than mass of Box B with its contents
= 9 u - 8 u
= 1 u
= 1 x 35
= 35 kg

Fraction of the sand that Box A had more than Box B
= ⁵₆ - ⁵₈
= ²⁰₂₄ - ¹⁵₂₄
= ⁵₂₄

⁵₂₄ of the capacity of sand in a box → 35
¹₂₄ of the capacity of sand in a box → 35 ÷ 5 = 7
¹⁵₂₄ of the capacity of sand in a box → 15 x 7 = 105 

Mass of the sand and Box B
= 8 u
= 8 x 35
= 280 kg

Mass of the empty box
= 280 - 105
= 175 kg

Answer(s): 175 kg