When an ice box is packed with 25 identical bottles of soda, it has a mass of 17.95 kg. When the ice box is packed with 30 identical packets of milo, it has a mass of 7.8 kg. A bottle of soda weighs 440 g more than a packet of milo. 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 milo = 1 P
Mass of 1 bottle of soda = 1 P + 0.44

Mass of 30 packets of milo = 30 P
Mass of 25 bottles of soda = 25(1 P + 0.44) = 25 P + 11 

Ice Box + 25 P = 17.95 - 11 = 6.95
Ice Box + 25 P = 6.95 --- (1)

Ice Box + 30 P = 7.8 --- (2)

(2) - (1)
30 P - 25 P = 7.8 - 6.95 
5 P = 0.85

1 P = 0.85 ÷ 5 = 0.17

25 P = 25 x 0.17 = 4.25

Mass of the empty ice box
= 6.95 - 4.25
= 2.7 kg

Answer(s): 2.7 kg