A container filled with 13 durians has a mass of 15 kg. The same container when filled with 5 oranges has a mass of 1.13 kg. The mass of 1 durian is six times the mass of 1 orange. Find the mass of the container when it is empty. Express the answer in g.
1 kg = 1000 g

15 kg = 15000 g
1.13 kg = 1130 g

1 orange = 1 u
5 oranges = 5 x 1 u = 5 u

1 container + 5 oranges = 1130
1 container + 5 u = 1130 --- (1)

1 durian = 6 u
13 durians = 13 x 6 u = 78 u

1 container + 13 durians = 15000
1 container + 78 u = 15000 --- (2)

(2) - (1)
78 u - 5 u = 15000 - 1130
73 u = 13870

1 u = 13870 ÷ 73 = 190

5 u = 5 x 190 = 950

From (1):
1 container + 5 u = 1130
1 container + 950 = 1130
 
1 container = 1130 - 950 = 180

Mass of 1 container = 180 g

Answer(s): 180 g