Which rule is executed first - Business Rule or Custom Trigger ?
When both Business Rule and a Custom Trigger is applied in an application, its the Business Rule that will be executed first before the Custom Trigger execution.
Business rules will be executed - Before the ticket is created.
Custom triggers will be executed - Post the ticket is created.
To see the history of the execution refer the History tab in related request. This details will be shown post 10.6 MSP Version.