Land recorded on gl at $7500 was sold on account for $10,000. What entries do I book to record the sale and the gain on the sale as well as the receivable and payment on account? Thanks.

The sale of the land should be recorded as follows:

Dr. Accounts receivable 10,000
Cr. Land 7,500
Cr. Gain on sale of land 2,500

When you receive the payment you should record the following entry:
Dr. Cash or bank
Cr. Accounts receivable

How to record the installment sales if we will used deferred gross profit?