Question

Oscar and Kim have $22.00 each to spend at a book fair, where all students receive a 30% discount. They both want to purchase a copy of the same book, which normally sells for $28.50 plus 10% sales tax. To check if he has enough to purchase the book, Oscar takes 30% of $28.50 and subtracts that amount from the normal price. He takes 10% of the discounted selling price and adds it back to find the purchase amount. Kim takes 70% of the normal purchase price and then computes 110% of the reduced price. Is Oscar correct? Is Kim correct? Do they have enough money to purchase the book? Explain your answer using complete sentences, and show your work.

Answer 1

They are both correct in their computation

(28.5-28.5(.3))+.1(28.5-28.5(.3))=$21.945

28.5(.7)(1.1)=$21.945

And since they each have $22 to spend, they have enough to purchase the book.

Answer 2

Oscar : 0.30(28.50) = 8.55....28.50 - 8.55 = 19.95...0.10(19.95) = 2....19.95 + 2 = 21.95

Kim : 0.7(28.5) = 19.95....1.10(19.95) = 21.95

They are both correct. They both have enough money to buy the book.
They each just did it a little different way. Kim, instead of taking 30% off, and subtracting it from the original price, she multiplied it by 70%...because taking 30% off is just like paying 70%....and instead of taking 10% of the discount price and adding it back to the discount price, she multiplied it by 110%....it is exactly the same thing