When an ice box is packed with 10 identical bottles of coke, it has a mass of 10.2 kg. When the ice box is packed with 15 identical packets of lemonade, it has a mass of 7 kg. A bottle of coke weighs 440 g more than a packet of lemonade. What is the mass of the empty ice box in kg?
1000 g = 1 kg
440 g = 440 ÷ 1000 = 0.44 kg

Mass of 1 packet of lemonade = 1 P
Mass of 1 bottle of coke = 1 P + 0.44

Mass of 15 packets of lemonade = 15 P
Mass of 10 bottles of coke = 10(1 P + 0.44) = 10 P + 4.4 

Ice Box + 10 P = 10.2 - 4.4 = 5.8
Ice Box + 10 P = 5.8 --- (1)

Ice Box + 15 P = 7 --- (2)

(2) - (1)
15 P - 10 P = 7 - 5.8 
5 P = 1.2

1 P = 1.2 ÷ 5 = 0.24

10 P = 10 x 0.24 = 2.4

Mass of the empty ice box
= 5.8 - 2.4
= 3.4 kg

Answer(s): 3.4 kg