A container filled with 9 durians has a mass of 6.46 kg. The same container when filled with 5 mangoes has a mass of 0.86 kg. The mass of 1 durian is five times the mass of 1 mango. Find the mass of the container when it is empty. Express the answer in g.
1 kg = 1000 g

6.46 kg = 6460 g
0.86 kg = 860 g

1 mango = 1 u
5 mangoes = 5 x 1 u = 5 u

1 container + 5 mangoes = 860
1 container + 5 u = 860 --- (1)

1 durian = 5 u
9 durians = 9 x 5 u = 45 u

1 container + 9 durians = 6460
1 container + 45 u = 6460 --- (2)

(2) - (1)
45 u - 5 u = 6460 - 860
40 u = 5600

1 u = 5600 ÷ 40 = 140

5 u = 5 x 140 = 700

From (1):
1 container + 5 u = 860
1 container + 700 = 860
 
1 container = 860 - 700 = 160

Mass of 1 container = 160 g

Answer(s): 160 g