A container filled with 9 mangoes has a mass of 9.93 kg. The same container when filled with 5 pears has a mass of 1.11 kg. The mass of 1 mango is six 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

9.93 kg = 9930 g
1.11 kg = 1110 g

1 pear = 1 u
5 pears = 5 x 1 u = 5 u

1 container + 5 pears = 1110
1 container + 5 u = 1110 --- (1)

1 mango = 6 u
9 mangoes = 9 x 6 u = 54 u

1 container + 9 mangoes = 9930
1 container + 54 u = 9930 --- (2)

(2) - (1)
54 u - 5 u = 9930 - 1110
49 u = 8820

1 u = 8820 ÷ 49 = 180

5 u = 5 x 180 = 900

From (1):
1 container + 5 u = 1110
1 container + 900 = 1110
 
1 container = 1110 - 900 = 210

Mass of 1 container = 210 g

Answer(s): 210 g