A box filled with 12 durians has a mass of 12.71 kg. The same box when filled with 8 pomegranates has a mass of 1.27 kg. The mass of 1 durian is eight times the mass of 1 pomegranate. Find the mass of the box when it is empty. Express the answer in g.
1 kg = 1000 g

12.71 kg = 12710 g
1.27 kg = 1270 g

1 pomegranate = 1 u
8 pomegranates = 8 x 1 u = 8 u

1 box + 8 pomegranates = 1270
1 box + 8 u = 1270 --- (1)

1 durian = 8 u
12 durians = 12 x 8 u = 96 u

1 box + 12 durians = 12710
1 box + 96 u = 12710 --- (2)

(2) - (1)
96 u - 8 u = 12710 - 1270
88 u = 11440

1 u = 11440 ÷ 88 = 130

8 u = 8 x 130 = 1040

From (1):
1 box + 8 u = 1270
1 box + 1040 = 1270
 
1 box = 1270 - 1040 = 230

Mass of 1 box = 230 g

Answer(s): 230 g