Leonard's home was damaged by a fire. He also had to be absent from work for several days to make his home habitable. Leonard's employer paid Leonard his regular salary, $2,500, while he was absent from work. In Leonard's pay envelope was the following note from the employer "To help you in your time of need" and $900, a collection from Leonard's fellow employees. Leonard spent over $4,000 repairing the fire damage.

Based on the above information, how much, if any, is Leonard required to include in his gross income?

$ X

The answer is not $600

I need help finding the X. Please show how you got your answer. Thank you!