We went over this online.
Anyway, if a method doesn't exist in the Employee class, you can't invoke that method using an Employee reference. You'd have to use one of the subclasses.
Employee ceo = new Exec("pergesu");
/* This line won't compile
ceo.getPctBonus();
*/
// Cast it to an Exec object, and invoke the method
((Exec) ceo).getPctBonus();
Put simply, if a method doesn't exist in a class definition, you can't call it. You have to cast it to a class type that does have the method. Exactly as I showed you online, as well as above.