A container filled with 9 durians has a mass of 10.25 kg. The same container when filled with 5 chikoos has a mass of 0.87 kg. The mass of 1 durian is eight times the mass of 1 chikoo. Find the mass of the container when it is empty. Express the answer in g.
1 kg = 1000 g

10.25 kg = 10250 g
0.87 kg = 870 g

1 chikoo = 1 u
5 chikoos = 5 x 1 u = 5 u

1 container + 5 chikoos = 870
1 container + 5 u = 870 --- (1)

1 durian = 8 u
9 durians = 9 x 8 u = 72 u

1 container + 9 durians = 10250
1 container + 72 u = 10250 --- (2)

(2) - (1)
72 u - 5 u = 10250 - 870
67 u = 9380

1 u = 9380 ÷ 67 = 140

5 u = 5 x 140 = 700

From (1):
1 container + 5 u = 870
1 container + 700 = 870
 
1 container = 870 - 700 = 170

Mass of 1 container = 170 g

Answer(s): 170 g