Sql query for calculation

Question

I have 4 tables

Purchase

Purchase Return

Sale

Sale Return

 

Data on purchase table

 

Data on purchase return table

 

Data on sale table

 

No data in sales return table

 

I want the sum of purchase price based on itemcode having same purchase price from all table

where pQty = Qty from purchase table

            PRQty = Qty from purchase return table and so on 

 

the calculation for

pQty of Itemcode =1  is 18 (10+8 from purchase table)

PRQty of Itemcode =1 is 3 (2+1 from purchase return table) and so on

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The final output 

 

The calculation for

closing qty of Itemcode 1 = 21 (sum of pQty- sum of PRQty - sum of SQty - sum of SRQty)

price of ItemCode 1 = 155 (

(sum of _PPrice- sum of _PRPrice - sum of _SPrice - sum of _SRPrice)

 

same calulation is applied in Itemcode 2

 

Please help me with the sql query