When an ice box is packed with 20 identical bottles of soda, it has a mass of 14.9 kg. When the ice box is packed with 35 identical packets of green tea, it has a mass of 8.15 kg. A bottle of soda weighs 480 g more than a packet of green tea. What is the mass of the empty ice box in kg?
1000 g = 1 kg
480 g = 480 ÷ 1000 = 0.48 kg

Mass of 1 packet of green tea = 1 P
Mass of 1 bottle of soda = 1 P + 0.48

Mass of 35 packets of green tea = 35 P
Mass of 20 bottles of soda = 20(1 P + 0.48) = 20 P + 9.6 

Ice Box + 20 P = 14.9 - 9.6 = 5.3
Ice Box + 20 P = 5.3 --- (1)

Ice Box + 35 P = 8.15 --- (2)

(2) - (1)
35 P - 20 P = 8.15 - 5.3 
15 P = 2.85

1 P = 2.85 ÷ 15 = 0.19

20 P = 20 x 0.19 = 3.8

Mass of the empty ice box
= 5.3 - 3.8
= 1.5 kg

Answer(s): 1.5 kg