$1 kg$ of ice at $0ºC$ is mixed with $1.5 kg$ of water at $45ºC$ [latent heat of fusion $= 80 cal/g$]. Then

On bringing of $1.5kg$ of water $45°c$ to $0°c$ heat released $=1500 \times 1\times 45 cal.$. 

mass of ice that melts with this heat $= \frac{1500\times 45}{80}=843.75 gm$ 

This is less than $1kg$so the resulting temperature is $0°c$.