I know this is such an easy question, but I completely forgot how to do it. Can someone please help me out? Thanks.

If 57.84 g of nickel (Cp = 0.0946 J/g Degrees C) originally at 97.4 degrees C is placed into a calorimeter with 48.24 g of water (Cp = 4.184 J/g degrees C), it is found that the final equilibrium temp is 37.2 degrees C. What must have been the original temp of the water in the calorimeter?

heat lost + heat gained = 0

[mass Ni x specific heat Ni x (Tf - Ti)] + [mass water x specific heat H2O x (Tf - Ti)] = 0.
Tf is final T. That is given as 37.2. Ti is the initial T. Solve for that. You are given mass Ni and mass water. Also you are given specific heat Ni and water. Ti is the only unknown. Post your work if you get stuck.