I buy land at 150,000 and sell it at 290,000. How would I post this transaction in my ledger in reference to accounting formula. ( Assets = Liabilities + Owners Equity).

If you sold the land, you're removing it from that account.

If you got 290,000 that's either cash or a receivable, depending on exactly what it says.

The difference is a gain, which like revenue is a credit.