A container filled with 11 mangoes has a mass of 12.84 kg. The same container when filled with 8 apples has a mass of 1.82 kg. The mass of 1 mango is six times the mass of 1 apple. Find the mass of the container when it is empty. Express the answer in g.
1 kg = 1000 g

12.84 kg = 12840 g
1.82 kg = 1820 g

1 apple = 1 u
8 apples = 8 x 1 u = 8 u

1 container + 8 apples = 1820
1 container + 8 u = 1820 --- (1)

1 mango = 6 u
11 mangoes = 11 x 6 u = 66 u

1 container + 11 mangoes = 12840
1 container + 66 u = 12840 --- (2)

(2) - (1)
66 u - 8 u = 12840 - 1820
58 u = 11020

1 u = 11020 ÷ 58 = 190

8 u = 8 x 190 = 1520

From (1):
1 container + 8 u = 1820
1 container + 1520 = 1820
 
1 container = 1820 - 1520 = 300

Mass of 1 container = 300 g

Answer(s): 300 g