Physics
posted by Jose .
How many grams of ice must be added to 100 grams of water at 60 degrees so that its temperature drops to 20 degrees celcius?
As far as i know I have to use:
(Mass)*(specific heat of water) *(finaltemperature  initial temperature = ??

What is the temperature of the ice when you put it in?
heat to lose=100*specifheatwater*40
heat absorbed by ice: mass*specificheatice*(Ti)+ mass*Heatfusionice*(20)
set them equal, after putting in Tinitial of ice, and solve for the mass of ice. 
the temperature of ice according to our physics teacher is 5 degrees celcius

Then
massice*(specificheatice)5+massice*heatfusionice*20= 100*spcificheatdwater*40