A man steals a $100 bill from a store’s cash register. Instead of leaving for good, he later returns to the same store and uses that exact $100 bill to buy $70 worth of merchandise.
The cashier, unaware that the bill was stolen from the register earlier, accepts it as normal payment. Because the purchase costs only $70, the cashier gives the man $30 in change.
At first, the situation can seem confusing because the store lost $100 when the bill was stolen, then received that same $100 bill back during the purchase. But once the stolen bill is returned to the register, that original cash loss is effectively canceled out.
What remains is the real damage: the man walks away with $70 worth of goods and also keeps the $30 in change the cashier gave him. Those are the two actual losses the store is left with.
So the correct answer is $100. The store loses $70 in merchandise plus $30 in cash, for a total loss of $100.