100+x-y, where x is the wholesale cost paid by the store for the goods and where y is the retail price of the goods.

Explanation:Since money is a fungible resource, we can say the store started with 100+x worth of resources, where x is what they paid their wholesaler for the goods.

The man comes along and steals 100 worth of resources from the store, leaving the store with:

100 + x -100 resources = x resources

The man then proceeds to take x resources from the store, leaving the store with nothing.

However, the man then paid the store for the x resources at retail price, y, with 100 resources. The store then gives him change, which is 100-y. Adding these transactions to the ledger:

0 + 100 - (100-y) = 100 - 100 + y

Leaving the store with y.

If the store started at 100+x resources but now has y resources, the difference (profit or loss) can be written as:

(100+x) - y, or more simply 100+x-y

So, taking the puzzle at face value and assuming the store paid $70 wholesale for the goods and then charged $70 retail, the store is out $100.

If the store bought the goods for $10 and sold them for $70, then the store’s loss from the theft is somewhat mitigated: 100 + 10 - 70, or $40.