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?

Respuesta :

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.
Add 87+19
106

Subtract 42 from 106
that makes 64

Answer, 42