Final answer:
The actual cash value of the roof that was destroyed is $500.
Step-by-step explanation:
To calculate the actual cash value of the roof that was destroyed, we need to subtract the total depreciation from the original cost of the roof. The total depreciation can be found by multiplying the annual depreciation ($300) by the number of years (10) since Sally bought the roof. So, the total depreciation is $300 * 10 = $3000.
To find the actual cash value, we then subtract the total depreciation from the original cost of the roof. Therefore, the actual cash value of the destroyed roof is $3500 - $3000 = $500.