Box S and Box T are identical. ⁵₆ of Box S and ²₅ of Box T are filled with sand. The mass of Box T with its contents is ⁸₉ the mass of Box S with its contents. The total mass of the two boxes with their contents is 442 kg. Find the mass of an empty box.
Mass of Box S and its contents = 9 u
Mass of Box T and its contents = 8 u

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

17 u = 442 

1 u = 442 ÷ 17 = 26

Mass of Box S with its concents more than mass of Box T with its contents
= 9 u - 8 u
= 1 u
= 1 x 26
= 26 kg

Fraction of the sand that Box S had more than Box T
= ⁵₆ - ²₅
= ²⁵₃₀ - ¹²₃₀
= ¹³₃₀

¹³₃₀ of the capacity of sand in a box → 26
¹₃₀ of the capacity of sand in a box → 26 ÷ 13 = 2
¹²₃₀ of the capacity of sand in a box → 12 x 2 = 24 

Mass of the sand and Box T
= 8 u
= 8 x 26
= 208 kg

Mass of the empty box
= 208 - 24
= 184 kg

Answer(s): 184 kg