When an ice box is packed with 10 identical bottles of soda, it has a mass of 7.6 kg. When the ice box is packed with 20 identical packets of milo, it has a mass of 5 kg. A bottle of soda weighs 450 g more than a packet of milo. What is the mass of the empty ice box in kg?
1000 g = 1 kg
450 g = 450 ÷ 1000 = 0.45 kg

Mass of 1 packet of milo = 1 P
Mass of 1 bottle of soda = 1 P + 0.45

Mass of 20 packets of milo = 20 P
Mass of 10 bottles of soda = 10(1 P + 0.45) = 10 P + 4.5 

Ice Box + 10 P = 7.6 - 4.5 = 3.1
Ice Box + 10 P = 3.1 --- (1)

Ice Box + 20 P = 5 --- (2)

(2) - (1)
20 P - 10 P = 5 - 3.1 
10 P = 1.9

1 P = 1.9 ÷ 10 = 0.19

10 P = 10 x 0.19 = 1.9

Mass of the empty ice box
= 3.1 - 1.9
= 1.2 kg

Answer(s): 1.2 kg