I made a loan management system using vb.net. I included income statement option(get interest income and expenses and calculate profit/loss) form to that software. I'm now face some problem.
what's that was I thinking really like this option needed to this loan management software.
Please give me advice guys !

My advice is to not make duplicate posts. I think I see more than two of the same question from you. Folk may notice and you'll get no replies.

That said, did you even take a course like System Design? These are not so much about programming but how to design a system with workflow, thinking about the end goal and then back to the beginning. You lay out the steps from beginning to end that you can then put into practice either with humans or automation (computers, apps, etc.)