A container filled with 15 durians has a mass of 8.06 kg. The same container when filled with 3 passion fruits has a mass of 0.65 kg. The mass of 1 durian is four 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

8.06 kg = 8060 g
0.65 kg = 650 g

1 passion fruit = 1 u
3 passion fruits = 3 x 1 u = 3 u

1 container + 3 passion fruits = 650
1 container + 3 u = 650 --- (1)

1 durian = 4 u
15 durians = 15 x 4 u = 60 u

1 container + 15 durians = 8060
1 container + 60 u = 8060 --- (2)

(2) - (1)
60 u - 3 u = 8060 - 650
57 u = 7410

1 u = 7410 ÷ 57 = 130

3 u = 3 x 130 = 390

From (1):
1 container + 3 u = 650
1 container + 390 = 650
 
1 container = 650 - 390 = 260

Mass of 1 container = 260 g

Answer(s): 260 g