$m = 250g = 0/25kg$${T_1} = 320K \Rightarrow {T_1} = {\theta _1} + 273 \Rightarrow 320 = {\theta _1} + 273 \Rightarrow {\theta _1} = {47^ \circ }C$$Q = mc\Delta \theta  \Rightarrow  - 4500 = 0/25 \times 900 \times \Delta \theta $$ \Rightarrow \Delta \theta  =  - {20^ \circ }C$$\Delta \theta  = {\theta _2} - {\theta _1} \Rightarrow  - 20 = {\theta _2} - 47 \Rightarrow {\theta _2} = {27^ \circ }C$