I don't any Thermochemistry so forgive my ignorance on this question.

An ice cube at 0.00 °C is placed in 200. g of distilled water at 25.00 °C. The final temperature after the ice is completely melted is 5.00 °C.

What is the mass of the ice cube? (ΔHfus = 340. J.g-1, Cp = 4.18 J.g-1.°C-1)

Answer=46.3 grams.

I tried heat lost = heat gained, but I'm not sure if this method is correct as I keep coming out with 49 g, which is not the correct answer. Any aid would be much appreciated.