Question

Dan has 20 books in his library. He bought several books at a yard sale over the weekend. He now has 71 books in his library. How many books did he buy at the yard sale?

Answer 1

To find the number of books he bought we need to do this:

# of books bought at yard sale = # of books after yard sale - # of books before yard sale

# of books bought at yard sale: x (we don't know what is yet)
# of books after yard sale: 71 books
# of books before yard sale: 20 books

Now set up the equation to solve: x = 71 - 20

Solve the equation:
71 - 20 = 51
so x = 51

Dan bought 51 books at the yard sale.

Answer 2

hi !!

He bought 51 books at the yard sale .

71 - 20 = 51


cheers !