When an ice box is packed with 10 identical bottles of soda, it has a mass of 8.3 kg. When the ice box is packed with 20 identical packets of green tea, it has a mass of 4.6 kg. A bottle of soda weighs 530 g more than a packet of green tea. What is the mass of the empty ice box in kg?
1000 g = 1 kg
530 g = 530 ÷ 1000 = 0.53 kg

Mass of 1 packet of green tea = 1 P
Mass of 1 bottle of soda = 1 P + 0.53

Mass of 20 packets of green tea = 20 P
Mass of 10 bottles of soda = 10(1 P + 0.53) = 10 P + 5.3 

Ice Box + 10 P = 8.3 - 5.3 = 3
Ice Box + 10 P = 3 --- (1)

Ice Box + 20 P = 4.6 --- (2)

(2) - (1)
20 P - 10 P = 4.6 - 3 
10 P = 1.6

1 P = 1.6 ÷ 10 = 0.16

10 P = 10 x 0.16 = 1.6

Mass of the empty ice box
= 3 - 1.6
= 1.4 kg

Answer(s): 1.4 kg