Simple logic: it is obvious that the debit side of process account is higher as the following are added(amounts) 8000+2000+4000+6000+640=24640.divided by total no of units i.e.20000+2000=22000. there fore the cost per unit will be 24640/22000= Rs.1.12/unit. The diff amount will be on the credit side of the process a/c as By tfd to Process B which comes to 20100 units at an amount of Rs.15120.
Case II:
The total side of the debit side of the process a/c is (amount)15000+52000+16000=83000 , the total no of units in the debit side of process a/c is 20000 units. The debit is greater than the credit by 14000 units at an amount of Rs. 62000.
Now use simple mathematical calculation
if 20000 units is 83000 how many units is 16000 , you will get 3856 units of R/M.
Therefore now you will get the cost per unit of R/M i.e. 16000/3856 = Rs. 4.149 per unit.
Hope you have under stood the logic behind procees a/c .