Final answer:
Ron's gain on the insurance reimbursement is $90,000.
Step-by-step explanation:
To determine the amount of Ron's gain or loss on the insurance reimbursement, we need to calculate the difference between his adjusted basis and the insurance claim amount. Ron's adjusted basis in the building was $210,000 and he was reimbursed $300,000. Therefore, his gain on the insurance reimbursement is $300,000 - $210,000 = $90,000.