During 2015, and office desk used by Pat and his business was completely destroyed

During 2015, and office desk used by Pat and his business was completely destroyed by a fire. The adjusted basis of the desk was $900 (original cost of $1500 less accumulated depreciation of $600). Pat received 500 from his insurance company, but he did not replace the desk.

a.) what is the amount of pets recognized gain or loss (deduction) as a result of the casualty?

b.) assuming this is Pat's only casualty gain or loss for 2015, what is the nature of the gain or loss?