When an ice box is packed with 25 identical bottles of coke, it has a mass of 23.4 kg. When the ice box is packed with 40 identical packets of orange juice, it has a mass of 12.7 kg. A bottle of coke weighs 590 g more than a packet of orange juice. What is the mass of the empty ice box in kg?
1000 g = 1 kg
590 g = 590 ÷ 1000 = 0.59 kg

Mass of 1 packet of orange juice = 1 P
Mass of 1 bottle of coke = 1 P + 0.59

Mass of 40 packets of orange juice = 40 P
Mass of 25 bottles of coke = 25(1 P + 0.59) = 25 P + 14.75 

Ice Box + 25 P = 23.4 - 14.75 = 8.65
Ice Box + 25 P = 8.65 --- (1)

Ice Box + 40 P = 12.7 --- (2)

(2) - (1)
40 P - 25 P = 12.7 - 8.65 
15 P = 4.05

1 P = 4.05 ÷ 15 = 0.27

25 P = 25 x 0.27 = 6.75

Mass of the empty ice box
= 8.65 - 6.75
= 1.9 kg

Answer(s): 1.9 kg