A container filled with 12 durians has a mass of 7.96 kg. The same container when filled with 3 kiwis has a mass of 0.76 kg. The mass of 1 durian is four times the mass of 1 kiwi. Find the mass of the container when it is empty. Express the answer in g.
1 kg = 1000 g

7.96 kg = 7960 g
0.76 kg = 760 g

1 kiwi = 1 u
3 kiwis = 3 x 1 u = 3 u

1 container + 3 kiwis = 760
1 container + 3 u = 760 --- (1)

1 durian = 4 u
12 durians = 12 x 4 u = 48 u

1 container + 12 durians = 7960
1 container + 48 u = 7960 --- (2)

(2) - (1)
48 u - 3 u = 7960 - 760
45 u = 7200

1 u = 7200 ÷ 45 = 160

3 u = 3 x 160 = 480

From (1):
1 container + 3 u = 760
1 container + 480 = 760
 
1 container = 760 - 480 = 280

Mass of 1 container = 280 g

Answer(s): 280 g