Linq Clean up

The logic is working and correct. I want to know if someone could help me write this in a clean robust way. I want short the lines of code if possible 

 

private DataTable AdjustTimesheetHours()

{

ColorDataSet.Tables[PrimaryTable].Columns.Add("adjustedHours");

foreach (var datarow in ColorDataSet.Tables[SummaryTable].AsEnumerable())

{

         string empno = datarow.Field("empno");

            double diffHours = datarow.Field("diffHours");

               var query = ColorDataSet.Tables[PrimaryTable].AsEnumerable().Where(s => s.Field("empno")

                                                                                                                                                            == empno && s.Field("task")

                                                                                                                                                               == "Regular" && s.Field("hrs") >= diffHours)

                                                                        .OrderByDescending(s => s.Field("hrs"))

                                                                        .FirstOrDefault();

double adjustedHours = 0;

if (diffHours > 0)

{

if (query.Field("hrs") >= diffHours)

{

            double hours = query.Field("hrs");

            string project = query.Field("project");

            string task = query.Field("task");

            adjustedHours = hours - diffHours;

               //Update datatable with adjusted hours

               ColorDataSet.Tables[PrimaryTable].AsEnumerable().Where(row => row.Field("empno") == empno &&                                                                                                                                                       row.Field("project")

                                                                                                                                                         == project && row.Field("hrs")

                                                                                                                                                      == hours && row.Field("task") == task)

                                                                     .Select(b => b["adjustedHours"] = adjustedHours)

                                                                        .ToList();

                     }

            }

      }

            return ColorDataSet.Tables[PrimaryTable];

}