Add manual filters in c# with and, or group expressions

[Malla reddy]

I'm trying for 

(student id=45624 and(college Id=4125 or college id  =78455 or college id=54521 ))

i tried with

 var id= new RadFilterEqualToFilterExpression<string>("student ");
                    id.Value = "45624";
                    RadFilterps.RootGroup.AddExpression(id);

  RadFilterps.RootGroup.GroupOperation = RadFilterGroupOperation.Or;

 var Cid1= new RadFilterEqualToFilterExpression<string>("college ");
                    Cid1Value = "4125 ";
                    RadFilterps.RootGroup.AddExpression(Cid1);

 var Cid2= new RadFilterEqualToFilterExpression<string>("college ");
                    Cid2.Value = "78455 ";
                    RadFilterps.RootGroup.AddExpression(Cid2);

 var Cid3= new RadFilterEqualToFilterExpression<string>("college ");
                    Cid3.Value = "54521 ";
                    RadFilterps.RootGroup.AddExpression(Cid3);