Which is cheaper?20% off the original price of $19.99 or 10% off its original price of $17 for a book?

If it is 20% off, then ur paying 80%

80% of 19.99 = 0.80 (19.99) = 15.99

if it is 10% off, then ur paying 90%

90% of 17 = 0.90 (17) = 15.30

so the cheaper one is : The $ 17 dollar book with the 10% off