A container filled with 8 jackfruits has a mass of 6.38 kg. The same container when filled with 4 chikoos has a mass of 0.66 kg. The mass of 1 jackfruit is seven 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

6.38 kg = 6380 g
0.66 kg = 660 g

1 chikoo = 1 u
4 chikoos = 4 x 1 u = 4 u

1 container + 4 chikoos = 660
1 container + 4 u = 660 --- (1)

1 jackfruit = 7 u
8 jackfruits = 8 x 7 u = 56 u

1 container + 8 jackfruits = 6380
1 container + 56 u = 6380 --- (2)

(2) - (1)
56 u - 4 u = 6380 - 660
52 u = 5720

1 u = 5720 ÷ 52 = 110

4 u = 4 x 110 = 440

From (1):
1 container + 4 u = 660
1 container + 440 = 660
 
1 container = 660 - 440 = 220

Mass of 1 container = 220 g

Answer(s): 220 g