Split Amount Based on condition for specific cell value.

Hello Again,

I am looking for a formula where the difference of amount split into the below listed values.

Details:

A user enter a Quantity in column B for each item. That Quantity which entered must not be maximum in column G.
That Quantity and the Quantity in column G deducted and the difference will be spilt in to the matched values.

For Example:
I a user put 3000 Quantity for DIMODAN HP 75/B MB but the actual Quantity is 8090 so the different for these items are 5090.
This 5090 will be divided into each same items mentioned below.

Let say DIMODAN HP 75/B MB found 2 times in below list then the amount will be divided into 2 times if it is 3 times then divided by 3 and so on...

Copy of expecting output is attached for your reference.

I have added more samples as requested please check the attachment v2

I am sorry. nothing should be done in column C & D.

As shown in the attachment. If a user enter a quantity in column B. First of all that quantity must not be more than in column G for that specific item.

then after the quantity entered in will be divided into below for same item.

Example: DIMODAN HP 75/B MB New qty is 3000 and the original is 8090. So how many times this items appear below in column A it will be divided that number of times.
in this case it will be count as 3 but need to divided into 2.