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 = ??

3 answers

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