A container filled with 15 durians has a mass of 11.53 kg. The same container when filled with 9 pears has a mass of 1.63 kg. The mass of 1 durian is five times the mass of 1 pear. Find the mass of the container when it is empty. Express the answer in g.
1 kg = 1000 g

11.53 kg = 11530 g
1.63 kg = 1630 g

1 pear = 1 u
9 pears = 9 x 1 u = 9 u

1 container + 9 pears = 1630
1 container + 9 u = 1630 --- (1)

1 durian = 5 u
15 durians = 15 x 5 u = 75 u

1 container + 15 durians = 11530
1 container + 75 u = 11530 --- (2)

(2) - (1)
75 u - 9 u = 11530 - 1630
66 u = 9900

1 u = 9900 ÷ 66 = 150

9 u = 9 x 150 = 1350

From (1):
1 container + 9 u = 1630
1 container + 1350 = 1630
 
1 container = 1630 - 1350 = 280

Mass of 1 container = 280 g

Answer(s): 280 g