A box filled with 8 jackfruits has a mass of 10.83 kg. The same box when filled with 9 chikoos has a mass of 1.9 kg. The mass of 1 jackfruit is seven times the mass of 1 chikoo. Find the mass of the box when it is empty. Express the answer in g.
1 kg = 1000 g

10.83 kg = 10830 g
1.9 kg = 1900 g

1 chikoo = 1 u
9 chikoos = 9 x 1 u = 9 u

1 box + 9 chikoos = 1900
1 box + 9 u = 1900 --- (1)

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

1 box + 8 jackfruits = 10830
1 box + 56 u = 10830 --- (2)

(2) - (1)
56 u - 9 u = 10830 - 1900
47 u = 8930

1 u = 8930 ÷ 47 = 190

9 u = 9 x 190 = 1710

From (1):
1 box + 9 u = 1900
1 box + 1710 = 1900
 
1 box = 1900 - 1710 = 190

Mass of 1 box = 190 g

Answer(s): 190 g