Question

The librarian counted 1,900 books in the library stacks before school started. The third week of school, 40% of the school library books were checked out.

How many books were in the library after 10% of the checked out books were returned

Answer 1

1900 * .40 = amount out

amount out * .10 = amount turned back in

1900 - amount out + amount back in = total amount in

Answer 2

40% of 1,900 = .4 times 1,900 = 760
so 760 were checked out, then 10% were returned, and 10% of 760 is 76

you good from there?

Answer 3

1216

Answer 4

1900 - (1900*.4)+(1900*.4*.1)

1900 (1 -.4+.4*.1)

1900 (1 -.4+.04)

1900 (1.04 -.4)

1900 (.64) = 1216