I have face the problem,i need to calculate the final amount if there is any booking fee and we charge service tax as 15% ST. If there is no Booking Fee then no ST,and if discount is there then we minus discount(percentage field) from the ticket price. It was working fine but now we offer discount amount(currency),but is not working.

My formula is

( (Quantity* UnitPrice ) - Discount_Amount__c ) + 
Booking_Fees_Amount__c + 
((((Quantity* UnitPrice ) - Discount_Amount__c )+ Booking_Fees_Amount__c)*PG__c) + 
ST_15_on_Booking_Fees__c

Discount_Amount_c is Percentage and Discount_c is Currency.

In my case sometime we give Discount percentage as well as whole amount percentage is working fine but whole amount is not working fine