A container filled with 9 honeydews has a mass of 7.88 kg. The same container when filled with 3 oranges has a mass of 0.74 kg. The mass of 1 honeydew is five 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

7.88 kg = 7880 g
0.74 kg = 740 g

1 orange = 1 u
3 oranges = 3 x 1 u = 3 u

1 container + 3 oranges = 740
1 container + 3 u = 740 --- (1)

1 honeydew = 5 u
9 honeydews = 9 x 5 u = 45 u

1 container + 9 honeydews = 7880
1 container + 45 u = 7880 --- (2)

(2) - (1)
45 u - 3 u = 7880 - 740
42 u = 7140

1 u = 7140 ÷ 42 = 170

3 u = 3 x 170 = 510

From (1):
1 container + 3 u = 740
1 container + 510 = 740
 
1 container = 740 - 510 = 230

Mass of 1 container = 230 g

Answer(s): 230 g