To calculate the price based on the difference points , please follow below steps:
Step 1: Go to Administration and click on configuration.
Step 2: Select Features and Options and click on Inventory tab.
Step 3: Here you see an option called Item Pricing Mode in Vouchers Click on that and choose as Party-Item-wise Price/Discount Structure and Select Mode as required.
Step 4: Now, go back to configuration and select Party-Item Price Structure and can select either Sale or Purchase.
Step 5: Next, you can set MRP, Price, Discount party item wise as per the requirements.