Try this,
var result = (
from
emp
in
DatabaseContext.Tblmst_Emp1
where
emp.Salary < 10000
group
emp by new { emp.Emp_Name} into e
select
new { e.Key.Emp_Name, Salary = e.Sum(x => x.salary)}
).OrderBy(x => x.Emp_Name)
.toList();
I hope this will help.
Thanks :)