35 of copper pellets are removed from a 300 oven and immediately dropped into 120 of water at 20 in an insulated cup.What will the new water temperature be?

I'm stuck on this problem and could use some help. I used q pellets = m · Cp · ΔT and q water = m · Cp · ΔT to try and figure out the problem, but am not getting the right answer. Aren't these the equations i use and then solve for Tf. For some reason my numbers aren't working.
Any help would be great.

1 answer

The sum of the heats gained is zero.

Heat gained by pellets+heatgained by water=0

masspellets(Cp)(Tf-300)+masswater(Cw)(Tf-20)=0
solve for Tf