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.
using complete senteces

Answer 1

Both Oscar and Kim are correct and do have enough money to purchase the book.

Using Oscars way:

Multiply the original price by the discount 28.50 x 0.30 = 8.55

Take that amount and subtract it from the price 28.50 - 8.55 = 19.95

Then multiply the discounted price by the sales tax rate 19.95 x 0.10 = 1.995 = 2.00

Add the sales tax amount to get the final cost 19.95 + 2.00 = 21.95 total cost

Kim's way:

Subtracting the discount percent from 100 percent ypu get 70 percent, so multiplying the price by 70 percent will get you the sale price 28.50 x 0.70 = 19.95

Multiplying the sale price by 110 percent calculates the tax amount plus the price together to get the final cost 19.95 x 1.10 = 21945 = 21.95 total cost

Both Oscar and Kim are correct and do have enough money to purchase the book.

Answer 2

Hello!

Oscar is correct, because all the steps he has taken to calculate the final price of the book are right and he has found the final price of the book.
Kim is incorrect because the steps she has taken to calculate the final price are not right, and she will not find the right final price.

YES, they have enough money to buy the book. Simply take all the steps Oscar took and calculate the final price.

28.50 × 30% = 8.55

28.50 - 8.55 = 19.95

19.95 × 10% = 1.995

19.95 + 1.995 = 21.945

This can be rounded to 21.95.

Since $21.95 is LESS than $22.00, they have enough money for the book.