I'm at a bookstore with 35$ in my pocket and a 20% -off coupon. What is the cost of the most expensive book I can buy with my money and the coupon? (Assume that there are books of every possible price in the bookstore. It's a large bookstore!)
You have enough cash to pay 80% of the book price, so 0.8*price = $35
Hence price = $35/0.8. = $43.75
