A container filled with 10 durians has a mass of 9.28 kg. The same container when filled with 9 passion fruits has a mass of 1.35 kg. The mass of 1 durian is seven times the mass of 1 passion fruit. Find the mass of the container when it is empty. Express the answer in g.
1 kg = 1000 g

9.28 kg = 9280 g
1.35 kg = 1350 g

1 passion fruit = 1 u
9 passion fruits = 9 x 1 u = 9 u

1 container + 9 passion fruits = 1350
1 container + 9 u = 1350 --- (1)

1 durian = 7 u
10 durians = 10 x 7 u = 70 u

1 container + 10 durians = 9280
1 container + 70 u = 9280 --- (2)

(2) - (1)
70 u - 9 u = 9280 - 1350
61 u = 7930

1 u = 7930 ÷ 61 = 130

9 u = 9 x 130 = 1170

From (1):
1 container + 9 u = 1350
1 container + 1170 = 1350
 
1 container = 1350 - 1170 = 180

Mass of 1 container = 180 g

Answer(s): 180 g