A box filled with 11 honeydews has a mass of 12.49 kg. The same box when filled with 6 lemons has a mass of 1.01 kg. The mass of 1 honeydew is eight times the mass of 1 lemon. Find the mass of the box when it is empty. Express the answer in g.
1 kg = 1000 g

12.49 kg = 12490 g
1.01 kg = 1010 g

1 lemon = 1 u
6 lemons = 6 x 1 u = 6 u

1 box + 6 lemons = 1010
1 box + 6 u = 1010 --- (1)

1 honeydew = 8 u
11 honeydews = 11 x 8 u = 88 u

1 box + 11 honeydews = 12490
1 box + 88 u = 12490 --- (2)

(2) - (1)
88 u - 6 u = 12490 - 1010
82 u = 11480

1 u = 11480 ÷ 82 = 140

6 u = 6 x 140 = 840

From (1):
1 box + 6 u = 1010
1 box + 840 = 1010
 
1 box = 1010 - 840 = 170

Mass of 1 box = 170 g

Answer(s): 170 g