A container filled with 9 honeydews has a mass of 9.72 kg. The same container when filled with 10 kiwis has a mass of 1.77 kg. The mass of 1 honeydew is seven times the mass of 1 kiwi. Find the mass of the container when it is empty. Express the answer in g.
1 kg = 1000 g

9.72 kg = 9720 g
1.77 kg = 1770 g

1 kiwi = 1 u
10 kiwis = 10 x 1 u = 10 u

1 container + 10 kiwis = 1770
1 container + 10 u = 1770 --- (1)

1 honeydew = 7 u
9 honeydews = 9 x 7 u = 63 u

1 container + 9 honeydews = 9720
1 container + 63 u = 9720 --- (2)

(2) - (1)
63 u - 10 u = 9720 - 1770
53 u = 7950

1 u = 7950 ÷ 53 = 150

10 u = 10 x 150 = 1500

From (1):
1 container + 10 u = 1770
1 container + 1500 = 1770
 
1 container = 1770 - 1500 = 270

Mass of 1 container = 270 g

Answer(s): 270 g