the desk is on sale, plus i can receive an extra $ 20 if i fill out and complete the mail-in rebate.
this class is very demanding (difficult, tough, challenge) , so i need to buy a good calculator to be able to do the homework.
my parents had sticker shock when they realized how expensive my school textbooks would be.
give in : to agree to something you were at first unwilling to do before as in. / i really don't want to help him move because i was so busy. but i finally gave in
buy into: believe something. don't buy into the idea that you have to be thin to be beautiful. it just isn't true.
if you don't have enough money to buy notebooks, i could chip in a few dollars to help you.
chip in: to add or contribute to something as providing help/ let's chip in and finish this project together.
threw in: an extra as a gratuity/ the store owner threw in an extra pair of earrings because i had bought so many other things.
