Tracy had 87 nickels. She used some of her nickels to buy a cookie. Tracy later found 19 nickels in her backpack. Now Tracy has 64 nickels. How many nickels did Tracy use to buy the cookie?

Add 87+19

106

Subtract 42 from 106

that makes 64

Answer, 42

42

Work backward. 64 at the end. She found 19. Take those away to see how many she had before that. 64-19=45. So she has 45 now. She started with 87. So to find out how many nickels were used for the cookie, subtract 45 from 87. 87-45=42.