100 g of water at 25 °C is poured into an insulating cup. 50 g of ice at 0 °C is added to the water. The water is stirred until the temperature of the water has fallen to 0 °C. 18 g of ice remains unmelted. The specific heat capacity of water is 4.2 J / g °C. Which value does this experiment give for the specific latent heat of fusion of ice? ​