The library has 3 nonfiction books for every 7 fiction books how many total books are there if the library has 240 nonfiction books

Question

if There are 3 nonfiction books for every 7 fiction books how many total books are there if the library has 240 nonfiction books

Answer 1

The library has either:

      3 N      and       7 F

or

      6 N      and       14 F

or

      9 N      and       21 F

or . . .

    240 N   and       560 F

 

This is a ratio problem:

     The library has 3:7 :: 240: x             or you could write:    3 / 7  = 240 / x

   Cross-multiply and solve:

        3x = 7*240

         x = 7*80

         x = 560