Iris wants to buy two necklaces, one for her sister and one for herself. the necklace for her sister costs $42.00, and the necklace for herself costs $28.00. the sales tax on the purchases is 8%. find the total cost of iris’s purchases, including sales tax. if necessary, round your answer to the nearest cent. a. show your setup and work, as well as your answer. b. explain what process you used to find the answer