Question

(03.01 MC)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.
By multiplying the original price of the book by 30%. Oscar is finding the amount of the discount. He then takes the discount off of the original price by subtraction. 28.50 * .30 = 8.55; 28.50-8.55 = 19.95; After he finds the new price he calculates the tax and adds it to the book price. 19.95 * .10 = 2.00 = $21.95
Instead of finding the amount of the discount, Kim found the amount she would have to pay after the 30% was subtracted from the 100%. This left 70% that had to be paid. 28.50 * .70 = 19.95; Then Kim knew that she had to pay this entire amount which was 100% plus another 10% for tax which is 110% so 19.95 * 1.10 = $ 21.95
Both Oscar and Kim got the same amount and they both had enough money to buy the book