When an ice box is packed with 10 identical bottles of soda, it has a mass of 11.3 kg. When the ice box is packed with 20 identical packets of coffee, it has a mass of 8.2 kg. A bottle of soda weighs 560 g more than a packet of coffee. What is the mass of the empty ice box in kg?
1000 g = 1 kg
560 g = 560 ÷ 1000 = 0.56 kg

Mass of 1 packet of coffee = 1 P
Mass of 1 bottle of soda = 1 P + 0.56

Mass of 20 packets of coffee = 20 P
Mass of 10 bottles of soda = 10(1 P + 0.56) = 10 P + 5.6 

Ice Box + 10 P = 11.3 - 5.6 = 5.7
Ice Box + 10 P = 5.7 --- (1)

Ice Box + 20 P = 8.2 --- (2)

(2) - (1)
20 P - 10 P = 8.2 - 5.7 
10 P = 2.5

1 P = 2.5 ÷ 10 = 0.25

10 P = 10 x 0.25 = 2.5

Mass of the empty ice box
= 5.7 - 2.5
= 3.2 kg

Answer(s): 3.2 kg