Question

purchase machinery of 100000 and old machinery personal value at 15000 was given it exchange and balance was paid by cheque

Answer 1

Machine A/c. Dr. 85000
To Bank. A/c. 85000

Answer 2

Old machinery Dr. 15000

To cheque 100000

To Bank A/c 85000

You need to understand that journal entry is just the entries with minimal words and all the essential points.

Hence, here the cost of old machinery, the amount paid through cheque and the actual amount paid to buy machinery is mentioned.