John wants to prepare a cold soft-drink using 0.2 kg of coke at 25 C and melting ice cubes of mass 0.025 kg each. At least how many ice cubes should be added to lower the temperature below 6 .C? (The specific heat capacity of water and the soft-drink are 4200 J kg 1 C- and 3470 J kg-1 C-1. The specific latent heat of fusion of water is 3.34 x 105 J kg-1.)