10 gm of ice at – 10⁰ C is mixed with 100 gm of water at 50⁰ C contained in a calorimeter weighing 50gm. (Specific heat of water = 1 cal. gm^{–1. 0}C^–1, Latent heat of ice=80cal/gm, specific heat of ice = 0.5 cal/gm / ⁰C and specific heat of copper = 0.09 cal/gm/⁰C). The final temperature reached by the mixtures is