@bronze
The store owner gets back $100 worth of liquid assets in the form of the bill, but loses $70 of hard inventory assets and $30 of liquid assets. At the time of theft and at face, the owner loses $100 worth of property, which is the answer to the logic question.

However, as others here have pointed out, there are other costs for the theft. The government got a share of the illegitimate $70 exchange, depending on the store's location, which I don't know can be written off by a CPA. The store also has to replace the goods lost to theft if the goods are not recovered. Even if they are recovered, the goods most likely cannot be sold for spoilage or other issues. So an extra $50-65 is lost to re-purchase new goods from manufacturers.

Then there is lost opportunity cost of the store owner using both the lost goods and lost currency, so the lost profit and other things must be factored in as well. Then there is any costs occurred if the owner purchases security measures beyond what he may already have before the theft. Then there are costs related to the legal process if the owner has to go to court, most likely as a witness for the persecution. The list goes on and on. For real life, it's not just $100.

Now you understand why the Biblical restitution punishment for thieves is to pay back or slave back twice to seven times the value stolen and why the American Jewdicial system is incompetent to its claimed mission and very evil.