Drop the owner part. How much did the store lose?
The markup is an important distinction, though lost revenue is a thing, but just like many textbook questions, this doesn't figure into the calculation.
My favorite is the woman who talked herself into stating that the store lost $270. Her being wrong was nothing special, but the magnitude in which she was wrong is pretty amazing.
Even ignoring the salary vs profit bits; it IS necessary to know if money gained by selling stuff counts as actual money gained; or whether it only counts as transferring assets from goods to cash.
In other words, if the theft hadn't happened, and someone walked in and bought $70 worth of stuff, would we say that the store made $70? There's 3 equally valid answers to that question:
1. The store made $70, because it has $70 more cash now than before.
2. The store didn't make anything, because although it has $70 more cash, it no longer has the items that could be sold for $70.
3. The store made whatever profit was made depending on the cost basis of the goods that were sold. So more than $0 but less than $70.
Which of the 3 answers you give to that question will determine the answer to "how much did the store lose in the theft?"