A guy walks into a store and steals a $100 bill from the register without the owners knowledge. He then buys $70 worth of goods using the $100 bill and the owner gives $30 in change.
How much money did the owner lose?
$30, $70, $100, $130, $170, or $200?
The best answer from the choices is the owner lost $100. The $100 bill that was stolen was then given back to the owner. What the owner loses is the $70 worth of goods and the $30 in change, which makes for a total of $70 + $30 = $100. The owner has lost $100.
Technically, the owner lost $30 plus the value, V, of the $70 of goods. Since stores typically sell goods at a markup, the value may be less than $70. But in the case of a loss leader, the owner may have lost more than $70.