The loss of precision is because the return type on get_monthlysalary() is int but _monthlysalary is a double value.
The other exception where it can't find the class is another typo. One package is called Employee and the other is employee. Java is case sensitive so these are different packages to the compiler.
You've still got a typo for _getDependents(), when you call this method in the test class you've spelled it differently
Also, your declarations for the methods in the employee class look like this
public void set_FirstName(String new_FirstName)
_FirstName = new_FirstName;
public void set_LastName(String new_LastName)
_LastName = new_LastName;
public void set_Dependents(int new_Dependents)
_Dependents = new_Dependents;
but when you call the methods, they look like this
You're missing the arguments when you call the methods.
Think that's it