Transaction: purchased land worth 54,000 for an office by paing 5,400 cash and sign a long-term note payable 48,600.

Would I put land in my journal even though the cash and note payable added together is equal to the land

Your journal entry is:
Debit Land for 54,000
Credit Cash for 5,400
Credit Notes Payable for 48,600

Note: Your Debits and Credits should always balance