When an ice box is packed with 20 identical bottles of coke, it has a mass of 11.4 kg. When the ice box is packed with 25 identical packets of orange juice, it has a mass of 5.35 kg. A bottle of coke weighs 330 g more than a packet of orange juice. What is the mass of the empty ice box in kg?
1000 g = 1 kg
330 g = 330 ÷ 1000 = 0.33 kg

Mass of 1 packet of orange juice = 1 P
Mass of 1 bottle of coke = 1 P + 0.33

Mass of 25 packets of orange juice = 25 P
Mass of 20 bottles of coke = 20(1 P + 0.33) = 20 P + 6.6 

Ice Box + 20 P = 11.4 - 6.6 = 4.8
Ice Box + 20 P = 4.8 --- (1)

Ice Box + 25 P = 5.35 --- (2)

(2) - (1)
25 P - 20 P = 5.35 - 4.8 
5 P = 0.55

1 P = 0.55 ÷ 5 = 0.11

20 P = 20 x 0.11 = 2.2

Mass of the empty ice box
= 4.8 - 2.2
= 2.6 kg

Answer(s): 2.6 kg