A box filled with 12 honeydews has a mass of 6.86 kg. The same box when filled with 6 passion fruits has a mass of 0.92 kg. The mass of 1 honeydew is five times the mass of 1 passion fruit. Find the mass of the box when it is empty. Express the answer in g.
1 kg = 1000 g

6.86 kg = 6860 g
0.92 kg = 920 g

1 passion fruit = 1 u
6 passion fruits = 6 x 1 u = 6 u

1 box + 6 passion fruits = 920
1 box + 6 u = 920 --- (1)

1 honeydew = 5 u
12 honeydews = 12 x 5 u = 60 u

1 box + 12 honeydews = 6860
1 box + 60 u = 6860 --- (2)

(2) - (1)
60 u - 6 u = 6860 - 920
54 u = 5940

1 u = 5940 ÷ 54 = 110

6 u = 6 x 110 = 660

From (1):
1 box + 6 u = 920
1 box + 660 = 920
 
1 box = 920 - 660 = 260

Mass of 1 box = 260 g

Answer(s): 260 g