When an ice box is packed with 10 identical bottles of soda, it has a mass of 8.3 kg. When the ice box is packed with 25 identical packets of coffee, it has a mass of 6.25 kg. A bottle of soda weighs 370 g more than a packet of coffee. What is the mass of the empty ice box in kg?
1000 g = 1 kg
370 g = 370 ÷ 1000 = 0.37 kg

Mass of 1 packet of coffee = 1 P
Mass of 1 bottle of soda = 1 P + 0.37

Mass of 25 packets of coffee = 25 P
Mass of 10 bottles of soda = 10(1 P + 0.37) = 10 P + 3.7 

Ice Box + 10 P = 8.3 - 3.7 = 4.6
Ice Box + 10 P = 4.6 --- (1)

Ice Box + 25 P = 6.25 --- (2)

(2) - (1)
25 P - 10 P = 6.25 - 4.6 
15 P = 1.65

1 P = 1.65 ÷ 15 = 0.11

10 P = 10 x 0.11 = 1.1

Mass of the empty ice box
= 4.6 - 1.1
= 3.5 kg

Answer(s): 3.5 kg