Dear student,
Latent heat of fusion is the amount of thermal energy which is required to melt a solid into liquid state or to freeze a liquid into solid state at a constant temperature.
Total heat required to melt a substance from solid to liquid= m*L
Here, m→mass ; L→latent heat per unit mass.
Now,using the above formula
Heat required= 80*4.6 = 368 calories
Regards