A box filled with 11 durians has a mass of 13.46 kg. The same box when filled with 5 mangosteens has a mass of 1.01 kg. The mass of 1 durian is eight times the mass of 1 mangosteen. Find the mass of the box when it is empty. Express the answer in g.
1 kg = 1000 g

13.46 kg = 13460 g
1.01 kg = 1010 g

1 mangosteen = 1 u
5 mangosteens = 5 x 1 u = 5 u

1 box + 5 mangosteens = 1010
1 box + 5 u = 1010 --- (1)

1 durian = 8 u
11 durians = 11 x 8 u = 88 u

1 box + 11 durians = 13460
1 box + 88 u = 13460 --- (2)

(2) - (1)
88 u - 5 u = 13460 - 1010
83 u = 12450

1 u = 12450 ÷ 83 = 150

5 u = 5 x 150 = 750

From (1):
1 box + 5 u = 1010
1 box + 750 = 1010
 
1 box = 1010 - 750 = 260

Mass of 1 box = 260 g

Answer(s): 260 g