Question

A man buys a book for $20 and wishes to sell it. What price should he mark on it if he wishes for a 40% discount and 50% profit on the cost price. Please explain your answer!

Answer 1

With that particular larcenous scheme in mind, he will price the book
regulaly at $50 . See the price-tag in the attached picture.

With a regular price of $50 written all over it, he can run a spectacular,
once-in-a-blue-moon, "40%-off" sale.

40% of $50 = 0.4 x $50 = $20 off

$20 off of $50 ===> Sale price = $30 is what the buyer will pay
during the spectacular sale.

Then, the sale price of $30 is (30/20) = 1.50 of his own original cost.

1.50 of his own cost means 0.50 = 50% more than he paid for it.