
2 answers
Hi Kiran, If you need this for Apex then below snippet code would help
IF (X == Y){
Start_Date__c = Start_Date__c.addDays(System.today().daysBetween(End_Date__c));
}

If you need this for Apex then below snippet code would help
IF (X == Y){
Start_Date__c = Start_Date__c.addDays(System.today().daysBetween(End_Date__c));
}