Final answer:
The insured should insure the property for $500,000 to comply with the 80% coinsurance provision of his insurance policy.
Step-by-step explanation:
To comply with the 80% coinsurance provision of his insurance policy, the insured should insure the property for $500,000. The insured should insure the property for 100% of the market value since the coinsurance provision requires the insured to carry insurance equal to a specified percentage of the property's value. In this case, the insured should carry insurance equal to 80% of the property's value, which is $500,000.