Not happy Marum!
Your plus should be a minus!
He lost the $30 plus he lost the goods sold, which had a wholesale cost of less than $70
Another way of looking at it is that to get back to status quo, the owner needs another $30 in the till and needs to re-stock the goods.
Let's say wholesale cost of goods is likely to be around $40 plus the $30 cash, so out of the selection $70 is about right.
