Opening a restaurant is not the best option for Sarah because she will incur an economic loss of $16k if she runs her restaurant.
$30k of equipment is not a cost. The reason is that she doesn’t have to throw them away when she finishes using them. In fact, she could re-sell them for a small amount of money but unfortunately, it would be the same as the price when she bought them. Which would result in a small loss which is called ‘depreciation’ in accounting.
$30k is the loss from value of Sarah’s non-current assets.